TWO FISH, ONE FISH

A fine plate of sand dabs is the kind of thing you can imagine the hero of a Raymond Chandler or Dashiell Hammett novel ordering, maybe at Musso & Frank in Hollywood or Tadich Grill in San Francisco. Just picture it: Simply sauteed or broiled in butter, the fish is delivered to a deep, leather-lined booth along with an icy martini or a bottle of the finest California “Chablis,� and then ceremoniously separated from its bones in two or three deft strokes by a white-jacketed waiter.

The hero takes a bite of the lean, minerally flesh, quaffs deeply of his drink and smiles before delivering a deadpan one-liner to the dame cuddled in beside him.

Unfortunately, even a detective as sharp as Philip Marlowe or Sam Spade would have a hard time tracking down a fresh sand dab today. Unless you’re willing to settle for frozen, this iconic California fish is exceedingly hard to find.

Not to worry. The ‘dab might be dead, but long live the rex. Rex sole, that is, a fish that is almost identical to the sand dab in all the most important ways. Its flesh is moist and firm, its flavor clean and sweet. Fry it or poach it, serve it simply with lemon and butter or gussy it up with a complicated cream sauce -- this fish is remarkably flexible.

Even better, it is among the most affordable in the market. While the newest, hottest wild salmon is going for $30 a pound, you can almost always find rex sole at $5 or $6.

First, though, don’t waste time mourning the ‘dab. This is no murder mystery. The sand dab isn’t really dead, just lying low due to recent changes in fishery regulations. In fact, you may not have even noticed it was gone; sand dabs and rex sole are so similar that some markets might be tempted to “confuse� the two and label the lesser-known rex as its more famous cousin.

If you’re curious, check the skin side of the fish: Sand dabs are brownish gray; rex sole is blackish gray. Other than that, it’s tough to tell.

Both sand dabs and rex sole are very small flatfish (whole fish average two or three to the pound). They’re so small, in fact, that they are very difficult to fillet. In the market they are usually sold in a form described as “pan ready,� which is two fillets joined to a central bone. These weigh anywhere from 2 to 5 ounces. Figure two per person for a main course; one will do for an appetizer.

Despite being extremely thin, the flesh is dense and takes heat well. You have to really overcook these fish to dry them out. Up to a point, the more well done they are, the better, as the fillet lifts more easily from the bone.

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A deep question

The most important difference between the two fish is that sand dabs are usually found in relatively shallow water -- they are most common between 120 and 300 feet -- while the rex sole is found slightly deeper -- up to 900 feet. That might not seem like much of a difference, but it is critical to commercial fishermen. A complicated series of regulations designed to protect threatened rockfish species has restricted various types of bottom fishing at less than 600 feet in many areas at different times of the year.

As a result, although both fish are plentiful in the ocean, according to the Monterey Bay Aquarium’s Seafood Watch program, fresh sand dabs are scarce in the markets, while rex is fairly common.

That’s the opposite of the way it was in the days of Chandler and Hammett, when sand dabs ranked right behind halibut as the most popular flatfish. More than 2 million pounds of sand dabs were caught in California in 1916, compared with less than 300,000 pounds in 2004. Rex sole wasn’t even tracked as a separate species until the 1930s, but it has certainly caught up: Landings in 2004 were nearly four times those of sand dabs.

Historically, the sand dab was highly concentrated in one port: Until after World War I, almost 90% of the catch was landed in San Francisco. This gave rise to a great tradition of ‘dab eating at the city’s many seafood grills, such as Tadich and Sam’s.

At these restaurants, there wasn’t much mystery in the cooking. The fish was usually treated simply, either broiled or served “meuniere� -- lightly dusted with flour and sauteed in hot butter. Prepared this way, the flesh develops a firm, meaty texture and, combined with a small sauce made from a little more butter and accompanied by a few steamed potatoes, this is where most traditional cooks leave it.

There’s certainly nothing wrong with that. But with a fish this good, why not try something different? Instead of plain potatoes, what about steaming a couple of other spring vegetables -- radishes and bulbing onions -- and then serving them as a kind of warm salad, dressed not with melted butter but with a tart, smoky bacon vinaigrette (yet another idea stolen from Thomas Keller’s wonderful “Bouchon� cookbook).

And why settle for sauteing? It turns out rex sole has a remarkably versatile flesh that adapts well to other kinds of cooking too. In fact, the way it varies with different cooking techniques is one of rex sole’s most interesting aspects. It is a fish with a thousand faces.

Poaching, for example, turns the flesh from meaty to moist. Cook rex sole with a little white wine and cream, surrounded by mushrooms above and below, and the fillets turn absolutely silky.

Or steam the fish, not by itself on the stove top, but in paper with other flavorings (parchment is the classic, but honestly, aluminum foil works better). Treated this way, the texture becomes somewhere between sauteed and poached -- firm but still velvety.

Lay a piece or two of rex on a sheet of foil, scatter sugar snap peas over the top and spoon some hazelnut- and lemon-flavored butter over everything, and you’ve got a terrific spring appetizer, which can be prepared well in advance and baked just before serving.

Wait until everyone is at the table to bring out the puffy foil packages. Then watch as the guests pop open these mysterious little gifts and are enveloped by the scented steam that billows out, the mingled scents of butter, hazelnuts, citrus and sweet sole meat.

Take a bite of the crunchy sugar snaps, then the silky fish. Swab up some of the butter and golden hazelnuts.

And that’s when it hits you. The only real mystery is why the rex sole isn’t better known already.

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How to deal with those tiny bones

Rex sole are so small that they are very difficult to fillet. Instead, you usually buy them “pan ready,� which means cut into pieces that look like fillets but have bones running down the center. These bones are easily removed after cooking.

Keep in mind that the bones look like a miniature fish skeleton, with a central spine and perpendicular pin bones springing from it. To remove the meat, cut a line down the center of the fish with a table knife, roughly along the main spine bone. Run the knife under half of the fillet and lift it off. Repeat with the other side.

Lift the very tip of the bone free of the underlying fillet and then carefully work the rest of it loose, lifting the spine with your fingers or a fork while separating bone from meat with the knife.

Do all of this with some care, as the bones are fragile and have a tendency to break apart.

The more well done the fish is, the more easily the meat will separate from the bones. Undercooking rex sole will result in a messy tug of war at the table. Fortunately, the fish handles extended cooking very well, so err on the side of caution.

-- Russ Parsons

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Sauteed rex sole with spring vegetable salad in bacon vinaigrette

Total time: 45 minutes

Servings: 6 to 8

Note: The dressing for this dish is adapted from Thomas Keller’s “Bouchon� cookbook. Bulbing spring onions are found at farmers markets, Whole Foods, Bristol Farms and Mexican groceries.

Bacon vinaigrette

3 strips bacon

Oil

1 teaspoon Dijon mustard

2 tablespoons Champagne vinegar

1 teaspoon salt

1. Cook the bacon in a skillet over medium-low heat, rendering the fat. Strain the bacon fat into a measuring cup and, if you are hungry, eat the bacon. Add enough oil to the bacon fat to make two-thirds cup.

2. In a blender, blend the mustard, vinegar and salt. With the blender running, slowly pour in the fat. It will create a thick emulsion. Scrape down the sides of the blender container and pulse again to combine. Set aside until ready to use. This vinaigrette can be refrigerated in a small, tightly covered jar for several days, but it will solidify. Before using, warm it gently to return it to a liquid state and shake it very well to re-emulsify.

Salad and assembly

1 1/2 pounds small new potatoes

1 teaspoon Champagne vinegar

2 bunches bulbing spring onions (about 6 to 8 onions)

2 bunches radishes

3 pounds pan-ready rex sole or sand dabs (10 to 12 pieces)

Salt

1 cup flour

3 tablespoons oil

Bacon vinaigrette

2 tablespoons minced parsley

1 tablespoon minced chives

1 teaspoon minced tarragon

1. Steam the potatoes until easily pierced with a fork, about 12 minutes. Transfer them to a bowl and sprinkle with the vinegar. When cool, cut them in half, if very small, or in quarters.

2. Trim the base of the roots of the onions, leaving a small amount of base intact to hold the onion together. Trim the green tops to make 3- to 4-inch pieces. Steam the onions until just tender, about

3 minutes. Remove from heat and cool slightly. Remove any tough outer skin and cut the onions lengthwise in quarters. Add to the potatoes.

3. Trim the roots of the radishes and trim the tops to within one-half inch of the radish. Steam the radishes just until the color and texture have barely softened, about 1 minute. Transfer the radishes to a separate bowl (their color will bleed if they are added directly to the potatoes). When cool, cut in quarters.

4. Cut the fish sections in half crosswise, on a slight bias. Season lightly with salt on both sides. Place the flour in a bowl and dredge the fish in the flour to lightly coat on both sides. Pat lightly to remove any excess.

5. Heat the oil in a large non-stick skillet over medium-high heat. When it is very hot, add half of the fish, being careful not to overcrowd the skillet (if necessary, cook the fish in three batches rather than two). When the fish is well browned on one side, about 5 minutes, turn and finish cooking on the other side, another 5 minutes.

6. While the fish is cooking, assemble the salad. Add the radishes to the potatoes and onions and drizzle with about 2 tablespoons of the vinaigrette. Toss to coat lightly, then sprinkle with salt and some of the minced parsley, chives and tarragon. Taste and adjust seasoning.

7. Arrange the salad in the center of 6 to 8 plates. As the fish is done, arrange it around the outside of the salad, propped up against it. Season the fish lightly with a drizzle of the remaining vinaigrette and a little of the minced herbs and serve immediately. Remove the fish bones before eating.

Each serving: 423 calories; 32 grams protein; 28 grams carbohydrates; 2 grams fiber; 20 grams fat; 6 grams saturated fat; 92 mg. cholesterol; 463 mg. sodium.

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Rex sole baked with mushrooms and cream

Total time: 1 hour, 5 minutes

Servings: 6 to 8

3 tablespoons butter

2 tablespoons minced shallots

1 pound white button mushrooms, sliced

Salt

2 1/2 to 3 pounds pan-ready rex sole or sand dabs (10 to 12 pieces)

1/4 cup white wine

3 tablespoons whipping cream

1 teaspoon minced parsley

1 teaspoon minced chives

1 teaspoon minced tarragon

1. Heat the oven to 400 degrees. Melt

the butter in a large skillet over me-

dium heat. Add the shallots and cook just until softened, 3 to 5 minutes.

Add the mushrooms and cook, stirring occasionally, just until they have begun to soften and color, 3 to 5 minutes. Season to taste with salt.

2. Spoon half the mushrooms in a thin layer across the bottom of a 3-quart gratin dish. Season the fish lightly on both sides with salt and arrange it in a single overlapping layer on top of the mushrooms.

Have the thinnest tail ends pointed to the ends of the dish and place the thickest pieces in the center. Spoon the remaining mushrooms over the top.

3. Moisten with the white wine (the

fish and mushrooms will produce more liquid as they bake) and cover tightly with aluminum foil.

Bake 15 minutes, then remove the foil, swirl in the whipping cream and return the dish to the oven until the fish flakes easily and the cream is bubbling, about 20 minutes more.

4. When the fish is cooked, sprinkle it with the minced parsley, chives and tarragon and serve immediately.

Remove the fish bones before eating.

Each of 8 servings: 214 calories; 30 grams protein; 3 grams carbohydrates; 1 gram fiber; 8 grams fat; 4 grams saturated fat; 99 mg. cholesterol; 130 mg. sodium.

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Rex sole and sugar snaps steamed in foil

Total time: 30 minutes

Servings: 8 appetizer servings

Note: To make 4 main-course servings, combine two pieces of fish and a quarter pound of sugar snaps in each of four packages along with the appropriate amount of hazelnut butter.

1/2 cup (1 stick) butter

3/4 cup chopped peeled hazelnuts

Grated zest of 2 lemons

3 tablespoons minced chives

1/2 teaspoon salt, plus more to taste

8 pan-ready rex sole (about 1 1/2 to 2 pounds)

Pepper

1 pound sugar snap peas, strings removed

2 lemons, quartered

1. Heat the oven to 450 degrees. Melt the butter in a small skillet or saucepan over medium-low heat. Add the hazelnuts and cook, stirring, until the smallest pieces begin to brown, 2 to 3 minutes. Immediately remove from the heat and continue stirring until the butter has cooled somewhat. Stir in the lemon zest, chives and one-half teaspoon salt.

2. Cut 8 (12-inch square) pieces of aluminum foil. Lay a piece of rex sole pale side up in the center of one and season the fish lightly with salt and pepper. Scatter about 2 ounces of sugar snap peas over top of the fish and spoon about 1 1/2 tablespoons of the hazelnut butter over the top. Crinkle the edges of the foil together to make an airtight package with some room left for expansion. Place the package on a baking sheet and repeat with the remaining ingredients.

3. Bake 15 minutes and then serve immediately, letting diners open their own packages. Pass the lemon wedges separately so diners can squirt a drop or two of lemon juice on the fish if they wish. Remove the fish bones before eating.

Each serving: 262 calories; 18 grams protein; 6 grams carbohydrates; 3 grams fiber; 19 grams fat; 8 grams saturated fat; 70 mg. cholesterol; 211 mg. sodium.