Fish skin. Normally, you nudge that dark, slimy heap to the side of your plate. You can see what it tastes like: low tide, trash. Why would anyone serve fish with its skin on?
Because when it's done right, the skin of many fish is exquisite, never more so than when it's crisped to a delicate wafer-thin crunch accompanying the sweet, soft flesh. Crisp fish skin should taste clean and fresh, with the concentrated flavor of the fish itself. Its colors and design are vivid on the plate. The fork clicks on its surface. It cracks brittlely beneath a knife.
Crisping fish skin is easy, but it brings the risk of overcooking the delicate meat. Fortunately, there are tricks to avoid that. The first and most critical step is to remove as much water from the skin as possible before you cook it. Skin will not crisp as long as there's moisture in it; until then, it will only steam. And if you try to get rid of that water by heat alone, the fish will overcook before the skin can crisp.
So remove some of that water mechanically, by drawing a knife blade firmly back and forth over the fish, the way a wiper blade moves across a windshield. The pressure compresses the skin and squeezes the water to the surface, and the knife blade carries it away. Repeat this until no more water rises to the surface.
If you need to store the fish, put it in a container skin side up so moisture doesn't sink back into the skin from the meat. Cover the container snugly, but leave a little room for air between the skin and the lid.
Finally, the pan you cook the filet in should be very hot but the oil should not be smoking. Lay the filet in it skin side down, pressing the fish with a spatula to keep all the skin in contact with the pan, and reduce the heat to medium. If you're cooking several pieces of fish, you may want to set a clean pan on top of the fish so you can press all of them at once.
How long you cook the fish will depend on how thick the skin is and how much water remains. When the skin is crisp, turn the fish over to complete the cooking.
This technique works best with salmon, black bass, striped bass, sea bass, arctic char, turbot, whitefish and cod. The fish should be meaty and the skin should be relatively thin. When you're cooking big pieces, scoring the skin can enhance the appearance, facilitate seasoning on the skin side and reduce buckling as well.
It's impossible to crisp the skin of some fish. Mullet and mackerel, for instance, are too oily to crisp (though they are still fine to cook and serve with the skin on).
We love crisp foods; they have an all but universal appeal. Though we usually think of fish as being soft, delicate and flaky, it does come with a perfect crisp component already attached, if you know how to achieve it.
Keller is chef at the French Laundry in Napa Valley. He and Ruhlman are coauthors of "The French Laundry Cookbook" (Artisan, $50). Ruhlman is the author of the upcoming "Soul of a Chef" (Viking, $20.95). Previous columns by Keller and Ruhlman can be found on the Times' Web site at http://www.latimes.com/keller.
Crisp-Skinned Salmon With Summer Succotash and Creamed Corn
Active Work and Total Preparation Time: 25 minutes
To dry the skin of the salmon, drag a knife blade gently but firmly over the skin several times, almost as if you are sharpening a razor on a strop. Use enough pressure to bring any water to the surface of the skin, then reverse direction to squeegee the water off the skin. Dry your blade and repeat until no more water rises to the surface. Place the filets skin side up in a covered container that allows space between the skin and the lid to facilitate more drying until it's time to prepare them.
1 cup fava beans, shelled, cooked until tender and shocked in ice water, skin removed
2 cups fresh corn kernels (about 2 ears), cooked until tender and shocked in ice water, plus 6 cups fresh corn kernels
1/2 cup diced red bell pepper
2 tablespoons chopped Italian parsley
1 tablespoon extra-virgin olive oil
3 tablespoons whipping cream
4 (4-ounce) salmon filets, skin dried by wiping with knife
3 tablespoons vegetable oil, for sauteing
* Saute fava beans, cooked corn, bell pepper and parsley in olive oil over low heat 3 to 4 minutes, then season with salt to taste and set aside at room temperature (this succotash can be prepared 2 hours before serving).
* Puree 4 cups fresh corn in blender or food processor (if using blender, you may need to add 1/4 cup water to facilitate blending). Remove to strainer and set over bowl or saucepan. Press solids to extract as much corn juice as possible, then discard solids. You should have 3/4 to 1 cup corn juice. (A vegetable juicer can be used instead.)
* Gently heat corn juice in saucepan until juice begins to thicken (don't boil). Add remaining 2 cups corn and whipping cream and cook gently until corn is tender, 1 to 2 minutes. Season with salt. Remove from heat and cover to keep warm.
* Season both sides of filets with salt. Heat pan over high heat. Add enough vegetable oil to cover bottom to depth of 1/8 to 1/4 inch. When oil is hot but not smoking, lay filets skin-side down, and reduce heat to medium (if using electric stove top, reduce heat before placing filets in pan). Press fish with spatula to flatten; if salmon curls, repeat. Cook until skin is crisp, about 3 minutes. Turn salmon and cook 10 seconds. Remove from pan and keep warm.
* Reheat succotash. Place spoonful of succotash in center of each plate. Spoon corn sauce around succotash. Place salmon filets skin side up on succotash.
4 servings. Each serving: 493 calories; 222 mg sodium; 65 mg cholesterol; 26 grams fat; 44 grams carbohydrates; 27 grams protein; 1.75 grams fiber.