Cook's Note: Look for top-loading hot dog buns, not New England-style rolls with cut sides.
Fill a stockpot with 1 to 2 inches of water and set over medium-high heat. Add the sea salt, peppercorns, seafood seasoning and onion. Once the water is boiling, add the lobsters. Cover the pot and steam the lobsters for 8 to 10 minutes. When finished, remove the lobsters and run under a blast of cold water.
Carefully remove the meat from the shell, saving the juices, and coarsely cut into large chunks (usually, the meat from 1 lobster is good for 1 roll). Mix the lobster juices with the mayonnaise; it should be a wet, thin consistency. Lightly toss the lobster meat with the mayonnaise.
In a small saucepan over medium heat, melt the butter along with a splash of crisp white wine and the garlic.
Heat a large, flat grill pan or skillet over medium heat. Open the buns, brush the butter mixture on the insides and toast, buttered-side down, until golden brown, about 1 minute.
Place the lobster meat on some foil and gently heat on the grill as the buns are toasting.
Evenly divide the lobster meat among the rolls, brush the meat with some butter mixture and serve in paper boats.