Live Crayfish: Dispatch by chilling in the freezer for at least an hour before cooking. Cooking freshly killed lobsters in boiling salted water turns the flesh from translucent to opaque. For a 600-800g lobster, boil for 10 minutes or steam for 15-18 minutes. If grilling, par-boil for 5 minutes, put into an ice bowl, remove meat and grill flesh-side down with oil or butter for approximately 5 minutes on each side. Be careful not to overcook lobster as this will make the flesh tough - cook only until the flesh begins to turn opaque.