Toss the lobster meat with 2 tablespoons melted butter, the shallots and tarragon in a medium bowl.
Brush the cut sides of the buns with the remaining 1/4 cup melted butter. Grill the buns, cut-side down, until golden brown, about 3 minutes. Dress the lettuce leaves with the olive oil, red wine vinegar, salt and pepper.
Place the dressed lettuce leaves in the toasted buns and add the lobster meat. Drizzle with the Spicy Mayonnaise and garnish with the chives. Serve with lemon wedges.
Combine the mayo, Dijon mustard, mustard powder, lemon juice, seafood seasoning and 1 teaspoon water in a bowl. Season with Sriracha and kosher salt.