How to Make It
Plunge the lobsters head first into a large pot of boiling water and cook until they turn bright red, about 10 minutes. Using tongs, transfer the lobsters to an ice bath to cool completely.
Twist off the bodies of the lobsters from the tails. Using scissors, cut along the underside of the tail shells and remove the meat. Halve the lobster tails, discarding the dark intestinal veins. Remove the meat from the claws and knuckles. In a bowl, stir the mayonnaise with the celery, lemon juice and tarragon. Cut all of the lobster meat into bite-size pieces and add to the bowl; season with salt and pepper and mix well. Refrigerate until chilled.
Heat a griddle. Brush the cut sides of the buns with butter and grill until toasted. Fill with the lobster salad and serve.