Lightly butter the insides of the buns or rolls and line with lettuce leaves. Set aside.
In a medium bowl, stir together the mayonnaise, lime juice, hot pepper sauce, salt and pepper until well blended. Mix in the green onion and celery, then lightly mix in the lobster so it just gets coated without falling apart.
Stuff the lobster filling into the buns and sprinkle parsley, basil or tarragon lightly over the filling.