Digging into a plate of cooked clams, only to wind up with a gritty mouth full of sand, is a clear sign that the clams were not cleaned and soaked beforehand. Most clams contain sand from constantly siphoning sandy ocean water through their shells, as they live on the ocean floor. Soaking the clams in water before cooking helps them spit out or purge the sand inside their shell, a crucial step before you can enjoy them. The sand-free clams can be cooked anyway you prefer, including steamed on the stove, baked in the oven or cooked on the grill.
Tap each uncooked clam whose shell is open gently against your countertop. Each one should close immediately upon the tapping. If any of the clams do not close back up, they are dead and should be discarded.
Rinse each clam under running water and scrub the shell of dirt or grit with a stiff brush.
Place the clams in a large bowl and cover them with cool water. Add about a gallon of water for every 2 pounds of clams you have, as well as 1/3 cup sea salt, which encourages the clams to spit out their sand.
Let them soak for about 30 minutes, then remove the clams individually from the bowl and into a colander. Drain the water in the bowl and refill with fresh water, then add the clams back to soak for another 30 minutes. Repeat the process another two or three times, until the water is clear of sand and grit.
Cook the clams as you wish, such as steaming them in white wine, grilling on a charcoal or gas grill or simmering in a flavorful sauce. The clams should be nearly free of sand if they have been soaked and purged properly.