Because of the highly perishable nature of crab meat, most crab legs are cooked right on the fishing boat or shortly after on the boat docks, then flash frozen. Only if you leave near a crabbing community and pick up a live crab will you get fresh, raw crab legs. That means that preparing crab legs typically only requires you to thaw and reheat them however you like.
King crab legs hail from Alaska and are the priciest -- but largest and sweetest -- type available. Snow crab legs sold in the United States largely come from Canada. Also known as Tanner crabs, snow crab legs are smaller and have a stringier texture. Crab legs labeled "fresh" have been cooked but thawed. Thaw frozen crab legs in the refrigerator overnight, or when you need them sooner, place them in a ziptop bag or other watertight container and run them under cold water until thawed.
On the stove top, use a steamer pot to reheat crab legs. Bring a small amount of water to a boil in the pot, then add the crab to the steamer insert. Cover and steam the crab for four to 10 minutes, depending on the size of the legs. When you can smell the aroma of crab, you know they are fully warmed. If you don't have a steamer pot, bring a pot of water to a roiling boil and fully submerge the legs for two to five minutes. Add them to the same pot as peel-n-eat shrimp and spices, such as Old Bay, for an old-style country boil. Fish markets and specialty stores often offer to steam the legs for you, so you don't have to worry about preparing them at all; the only catch is that you must eat them soon after arriving home.
To bake crab legs, place them in a baking pan and add just a little water -- but not quite enough to completely submerge the legs. Top the pan with foil and bake the crab in a 350-degree oven for three to 10 minutes. Crab legs may also be prepared on a charcoal or gas grill. Place them in a moderately hot section and cook three to five minutes per side.
The sweet flavor of crab legs shines when they're served cold with a complementary sauce. Simply allow them to thaw, cut them open with kitchen shears and serve. Stir together lemon juice and mayonnaise with a sprinkle of lemon zest for an easy accompaniment. For a dip with an unexpected punch, mix mayonnaise with a splash of brandy, ketchup and sour cream. Other sauces accompany crab legs include an emulsification of chives, olive oil and lemon juice, or a blend of spicy red pepper flakes or thai chiles and clarified butter. Homemade or store-bought diablo, tartar and ponzu sauces also complement steamed or chilled crab legs.