The sweetest and tenderest lobsters are under 1½ pounds, and the easiest way to cook live lobsters is by boiling or steaming them.
To boil lobsters, fill a lobster kettle with water to cover the lobsters and add 1 teaspoon of salt for every quart of water if you are not using sea water. Cover the kettle and bring to a rolling boil.
Plunge the lobsters head first into the pot and cover. When the water begins to boil, cook the 1-pound lobsters for 10 minutes, 1¼-pound lobsters for 12 minutes, and 1½-pound lobsters for 14 minutes. Cold live lobster will cool down the water and it will take from 3 to 5 minutes for the water to return to a boil.