Contrary to popular belief, to obtain tender flesh, seafood such as lobsters, shrimp and crabs should be simmered, not boiled.
In a large saucepan deep enough to immerse the lobsters, put 1 tablespoon of coarse salt for 4 cups of cold water. Bring to a boil.
Remove the elastic bands from the lobsters using scissors a few minutes before cooking them. While holding the lobsters by the body just above the little legs, add them to the pot, head first. Bring to a boil again, reduce heat and simmer (small bubbles rise to the surface) 15 minutes per pound of lobsters and not 15 minutes per total weight of lobsters. Add 5 minutes for each additional pound. So a 1 kg (2 lbs) lobster will take 20 minutes to cook.
As soon as the cooking is finished, remove the lobsters from the pot using kitchen tongs and rinse with cold water for about 15 seconds. Place the lobsters on the back until ready to serve so that the flesh remains juicy. Never let the lobsters soaking in their cooking water.