In a medium bowl, whisk together mayonnaise, green onion, lemon juice, and salt and pepper to taste (I like 1/4 teaspoon salt and 1/8 teaspoon pepper). Fold in lobster and celery. Cover and chill until serving time.
Spread butter on outside of buns. In a large skillet or griddle over medium-high heat, toast buns until golden brown, about 2 to 3 minutes per side.
Fill each toasted bun with about 1/2 cup lobster filling and serve with lemon wedges.
Lobster: 1 pound of lobster claws and arms yields about 2 cups meat (reserve tails for something special such as Surf and Turf). If frozen, thaw overnight in the refrigerator. If raw, steam with salted water until cooked through, about 4 to 6 minutes.
Buns: Also known as New England-style buns, these hot dog buns and sliced through the top instead of through the side. Grilling the buns is optional but recommended.
Yield: This Lobster Roll recipe makes about 2 cups of cold lobster filling, enough for 4 sandwiches with 1/2 cup filling each.
Storage: Store covered in the refrigerator for up to 2 days.
Make ahead: Get ahead of the game by making the lobster filling a day in advance.