SHRIMP

COOKING SHRIMP IS A RELATIVELY STRAIGHT forward process. As soon as the meat turns pink (which can happen in just two or three minutes over intense heat), the shrimp are done. How the shrimp are handled before cooking actually generates more confusion. Should they be peeled? Should the vein that runs down the back of each shrimp be removed?

There are two basic ways of cooking shrimp, either with dry heat (for example, grilling or pan-searing) or moist heat (for example, poaching or steaming). After some initial tests, we concluded that shrimp must be prepared differently when cooked by dry and moist heat. We found that when shrimp are grilled or pan-seared, the shell shields the meat from the intense heat and helps to keep the shrimp moist and tender. Try as we might, we found it impossible to grill or pan-sear peeled shrimp without overcooking them and making the meat dry and tough, especially the exterior layers. The only method that worked was to intentionally undercook the shrimp; but that left the inside a little gooey, something that almost no one enjoyed.

When shrimp are cooked in liquid the tables turn, and it is best to peel them first. The exterior of shrimp cooked in liquid are not as prone to drying out, and the shells can be simmered in the liquid to increase its flavor. Also, it is nearly impossible to peel shrimp cooked in hot liquid. While the peel separates easily from grilled or pan-seared shrimp, the shells become firmly attached to the meat when the shrimp are cooked in liquid.

In addition to peeling, the issue of deveining generates much controversy among experts. Although some people won't eat shrimp that has not been deveined, others believe that the "vein"—actually the animal's intestinal tract—contributes flavor and insist on leaving it in. In our tests, we could not detect an effect (either positive or negative) on flavor when we left the vein in. The vein is generally so tiny in most medium-sized shrimp that it virtually disappears after cooking. Out of laziness, we leave it alone. In larger shrimp, the vein is usually larger as well. Very large veins can detract from the overall texture of the shrimp and are best removed before cooking.

One more step worth taking when preparing shrimp for dry cooking is to brine them in a salt solution. Brining causes shrimp to become especially plump (they may gain as much 10 percent in water weight) and firm. The science is fairly simple. Salt causes protein strands in the shrimp to unwind, allowing them to trap and hold onto more moisture when cooked. At its most successful, brining turns mushy shrimp into shrimp with the chewy texture of a lobster tail. Even top-quality shrimp are improved by this process. We tested various concentrations of salt and brining times, and in the end settled on soaking shrimp in a strong salt solution (three cups kosher salt dissolved in five and one-half cups water) for 20 to 25 minutes.

Once the shrimp has been brined, it can be dumped into a hot skillet or threaded onto skewers and grilled. Unpeeled shrimp is easy to cook either way. As soon as the meat turns pink, the shrimp are done. We found that shrimp should be cooked quickly to prevent them from toughening. This means using a very hot skillet or a hot grill fire.

When pan-searing, it's easy enough to make a quick pan sauce once the shrimp have been cooked and transferred to a bowl. Just add some oil and seasonings (garlic, shallots, lemon juice, herbs, spices) to the empty pan and cook briefly. The sauce can then be tossed with the shrimp in the shell to coat them. When grilling, we like to coat the shrimp with a paste or marinade before cooking. With both pan-searing and grilling, the flavorings adhere to the shell beautifully. When you peel the shrimp at the table, the seasonings stick to your fingers and they are in turn transferred directly to the meat as you eat it. Licking your fingers also helps.

When poaching shrimp for cocktail or salad, brining is not necessary—the shrimp remain nice and plump when cooked in liquid. The issue here is how to flavor the shrimp as it cooks. If you start with good shrimp and simmer them in salted water until pink, the shrimp will have a decent but rarely intense flavor. Cooking them in their shells (which actually contain a lot of the "briny" flavor we associate with good seafood) helps improve the flavor of the shrimp, but the cooked shrimp are very hard to peel. When steamed, the shells attach to the meat, and it becomes hard to remove them without tearing the meat below. In addition, we found that it takes a good 20 minutes for the shells to give up their flavor. Clearly, the shrimp meat will be long overcooked by this time.

Our solution is to peel the shrimp and simmer the shells alone with the salted water to make a quick stock. To give the stock even more flavor, we tried adding other ingredients to the strained stock. After trying a dozen different combinations, involving wine, vinegar, lemon juice, and various herbs and spices, we found that a mixture of three parts quick shrimp stock to one part white wine, with a dash of lemon juice and some traditional herbs (bay leaf, parsley, and tarragon) does the best job of flavoring the shrimp as it cooks. At higher concentrations, the wine and lemon juice are too overpowering.

At this point in our testing, we liked the flavor of our poached shrimp but wondered if prolonging the cooking time (and hence the time the shrimp was in contact with the flavorful broth) would improve its flavor. We tried lowering the heat but found that it was too easy to overcook the shrimp and make it tough. What worked best was to bring the broth to a boil, turn off the heat, add the shrimp, and cover the pot. The shrimp can stay in the liquid for 10 minutes or so (as opposed to just 2 or 3 minutes if the liquid is boiling), enough time to really pick up the flavor of the liquid.

In addition to dry-heat cooking or poaching, there are two other cooking methods for shrimp worth considering. True shrimp scampi contains peeled pink shrimp floating in plenty of garlicky sauce that can be used to moisten bread or rice. The challenge is cooking the shrimp in a skillet in such a way that will produce these wonderful juices.

We added every liquid we could think of—white wine, lemon juice, fish and chicken stock, even water—but were disappointed. Olive oil didn't work either. The wine and lemon juice added too much acidity, extra oil made the dish greasy, and the stocks and water diluted the flavor of the shrimp. During these tests, we also noticed that an overly high heat makes the garlic too brown and also toughens the shrimp.

When we lowered the heat the liquid given up by the shrimp lingered in the pan. We set out to cook the shrimp more slowly, in effect braising it in olive oil and its own natural juices. Because our goal was to preserve the liquid and tenderness of the shrimp rather than create crispness, the technique is closer to braising than sautéing.

Once we started to move in this direction, everything fell into place. With lower heat, the garlic becomes tender and mellow, the olive oil retains its freshness, and the shrimp remains moist and tender.

Our last experiments involved deep-frying shrimp. We tested a variety of coatings and preferred a simple one made with bread crumbs. It was crisp and crunchy (we found that a crunchy coating offers a nice contrast with tender shrimp and other shellfish), and it browns nicely. When we tried dredging the shrimp in flour then dipping it in egg and rolling it in bread crumbs, the coating separated from the shrimp. We preferred just egg and then bread crumbs since the coating rests right on the shrimp and offers the best contrast in textures. Cornmeal lacked the same crunch and color. A beer batter was too puffy and light, and the beer flavor detracted from the seafood flavor. Also, the beer batter is not at all crunchy but soft. A mixture of flour and milk made a pasty coating with no crunch, and adding some egg to the batter didn't do much to improve it.

As for the frying medium, we found that peanut and corn oil were the most flavorful. Canola and vegetable oil were fine, if less flavorful.

A final note about buying shrimp. There are more than 300 species of shrimp grown around the world. (There is such a thing as "wild" shrimp, but most shrimp is farm-raised.) Black tiger shrimp from Asia is the most common variety sold in U.S. markets. It can be firm and tasty, but the quality is inconsistent. In our taste tests, we preferred Mexican whites from the Pacific Coast and Gulf whites. They were the firmest and had the strongest fresh-from-the-sea flavor. However, we didn't like all the white shrimp we tasted. Chinese white shrimp were decidedly inferior to both the Mexican and Gulf white shrimp and to most of the tiger shrimp.

In general, the flavor and texture differences in various species are most noticeable when shrimp is poached and used in shrimp cocktail. Our advice is simple: If you have a choice, look for white shrimp from Mexico or the Gulf, especially when making shrimp cocktail.