Cook the lobster and remove the meat. Boil or steam the lobster for 9-15 minutes, adjusting the time according to the weight. Use a lobster cracker to remove the meat from the claws, knuckles, and tail. But the meat into bite sized chunks, then place in a mixing bowl.
Combine all the ingredients. Add the mayonnaise, chopped celery, lemon juice, salt, and pepper to the lobster in the mixing bowl. Stir to combine. Place the mixture in the fridge for atleast an hour if you want the cold "Maine style" lobster rolls.
Toast the buns. Slather the butter on all sides of the buns, then place them on a griddle over medium heat. Allow each side to toast.
Stuff the rolls. Once the buns are toasted, place a layer of lettuce in them, then stuff them to the brim with the lobster mixture. Dig in! Mangia!