Monkfish “Lobster” Rolls

1 1/2 teaspoons celery saltKosher salt and freshly ground pepper3 tablespoons Unsalted Butter1/3 cup mayonnaisejuice of 1/2 lemon1 cup stalk celery (finely chopped)4 split-top hot dog rollsBibb lettuce leaves (for serving)3 tablespoons chopped fresh chives Main...