GRILLED SEAFOOD

SALMON IS THE EASIEST FISH TO GRILL BECAUSE it is oily, and therefore harder to overcook. However, salmon often sticks to the grill and tears. Our testing revealed that a medium-hot fire browns without burning and, more importantly, creates the necessary crust so that the salmon can be flipped easily. Oiling the skin does not keep it from sticking and can cause flare-ups. We prefer to rub the grill grate with a wad of paper towels dipped in vegetable oil before cooking any fish.

Center-cut fillets are almost always 1¹/₂ inches thick and ideal for grilling; thinner pieces cut from the tail tend to overcook, and thick pieces from the head can take too long to cook through. The grill cover can impart a smoky, fatty flavor to the fish, so leave it off.

Tuna and swordfish have much less fat than salmon, so drying out is a real threat on the grill. By the time these steaks are seared, the inside can be dry and unappetizingly fishy, especially if the steaks are thin. We found a hot fire will produce well-seared fish that is moist inside.

If you want these fish rare or medium-rare, they must be cut about 1¹/₂ inches thick. But you can't always get thick steaks. The standard supermarket cut is ³/₄ to 1 inch thick. By the time a piece of tuna or swordfish this thin is seared, the fish is overcooked. Something must be done to thin-cut tuna and swordfish before it hits the grill. After testing various marinades, we found that soaking the fish in olive oil does the best job of keeping the texture moist and luscious, even in thin steaks cooked to medium and beyond.

According to the food scientists we spoke with, the oil penetrates and coats the strands of protein in tuna and swordfish so that the fish feels moist in the mouth, even after most of the moisture has been cooked out. Oils high in emulsifiers—such as mono- and di-glycerides—penetrate protein more quickly than oils containing less of these agents. Extra-virgin olive oil contains both these emulsifiers and also adds flavor to the fish.