Grilling gives a smoky flavor and crisped texture to finfish and shellfish. It works best for meatier, firmer-fleshed finfish cut in to steaks or fillets with skin. However, flakier finfish, skinless fillets, and smaller shellfish (that would otherwise slip through the grill grates) can be grilled using a grill basket. Grill baskets are non-stick wire cages-with a top, bottom, and long removable handle-that hold food firmly in place so that it can easily be flipped or removed from the grill.
Prepare seafood for grilling by very lightly spraying both sides of it with olive oil or vegetable oil (away from direct flames). Spraying with oil rather than brushing or rubbing the oil in with your hands avoids contact with raw seafood to prevent cross-contamination with other foods you may be grilling. Once oiled, season seafood with salt and pepper. Or, marinate the seafood in your favorite combination of juice, herbs, spices and oils. Shake off excess marinade before grilling to avoid flare-ups.
If using a gas grill, begin by preheating it for at least ten minutes on the highest setting with the lid closed. For charcoal grills, allow the fire to burn down so that you can comfortably hold your hand above the coals for only two to three seconds. At the proper cooking temperature, the coals will glow softly and be covered with a thin layer of ash. Next, clean the grate by scraping it with a grill brush then wiping it with a wad of paper towels dipped in a light coating of oil (grasp the paper towels with tongs to avoid burning your fingers). Both a very hot grill and a clean grill grate will help prevent seafood from sticking.
Finfish, large shrimp, and scallops may be placed directly on the grill grates and cooked until opaque. Smaller varieties are easier to turn if placed on water-soaked wooden skewers or in a grill basket. Shellfish, including mussels, clams and oysters, may be placed directly on the grill and cooked until their shells open-about five minutes. Discard any that do not open after cooking. With a little more preparation, whole lobsters and crabs may be grilled, but grilling lobster tails and king crab legs is an easier (and just as delicious) option.
As a general rule, seafood steaks and whole fish will take about 10 minutes to cook for each inch of thickness (measured in depth, not length). Thin fillets will take less time. If fillets have skin, place them skin side down and do not move the fish for at least two minutes to build up a crust that won’t stick. If grilling smaller fillets, make a few shallow slashes through the skin, which will keep the fillet from curling as the skin cooks and shrinks.