There is nothing fancy about lobster rolls; they were invented on the side of the road. I think my secret is steaming the lobster in a salty bath and never tossing out the lobster liquids that are in the shells. Save every last drop. That liquid is like lobster extract . . . or lobster flavor on steroids. Trust Dr. Klaw on this one.
In a large clam or lobster pot, add 2 inches of water. Put in the onion halves cut sides down and add the coarse sea salt, garlic, bay leaves, and black peppercorns. Bring to a boil over high heat.
Put in the lobsters head up, the first 2 sitting on the onion halves, and loosely stack the other 2 lobsters, making sure all the lobsters are evenly spaced apart. Cover and cook over medium-high heat until bright red all over, about 6 minutes. They will be a little undercooked for a reason!
Transfer the lobsters to a large rimmed baking sheet and let cool. Work over the sheet to collect all the lobster juices and fat. Twist the tails and the claws from the bodies. Pull off the tail ends or flippers from the tail shells and push the tail meat out of the shells with your thumb. Cut down the top of the tails and discard the dark vein. Twist the knuckles from the claws. Cover the claws with a kitchen towel and with a mallet or the back of a large knife, gently crack the claws on both sides to loosen the shells from the meat. Break the shell off of the claws and pull out the claws, preferably each in one piece. Break up the knuckles and push out the meat.
Cut the tails down the center and give all of the lobster meat just a few chops; the meat should be in nice chunks. You should have about 5 cups of meat. Put the meat and all of the collected juices in a large skillet and set aside.
Now heat a griddle. Meanwhile, in a small saucepan, melt the butter with the garlic powder and stir. Open the hot dog buns and brush only the insides with some of the garlic butter. Toast the buns on the hot griddle on medium-high heat until golden brown and crisp, about 2 minutes per side. Reduce the heat to medium if the griddle gets too hot.
Very gently reheat the lobster meat over low heat until barely hot. Remove the skillet from the heat, stir in the mayonnaise, and season with fine sea salt. Pack the lobster meat into the toasted buns and drizzle each with a little more of the garlic butter. Sprinkle with Old Bay seasoning and serve right away. You should have a nice pink-orange sauce developing around the meat as a result of the mayo and lobster juice cooking just a bit.