The ideal way to cook a frozen whole lobster is to thaw the lobster entirely, then to cook it in saltwater for up to 15 minutes depending on the weight of the lobster. The boiling water should be a 2 percent salt mix; for example, if using 6 quarts of water, then add about 4 tablespoons of salt.
When thawing frozen lobster, it is advisable to do so overnight in a refrigerator. Place the lobster in a bowl or other container of cold water and salt, similar to the mixture used to cook the lobster, then add the lobster. All lobster should be cooked and eaten within 36 hours of being thawed.