Finely dice the water chestnuts. Toss into a mixing bowl with egg, teriyaki sauce, breadcrumbs, onion powder, salt and ground turkey. Mix together and then shape into 4 burger patties.
Preheat and indoor grill or if the weather permits, use the outdoor grill. Cook each burger for 6-8 minutes per side, or until no longer pink in the center.
While burgers cook pull off 4 large leaves for the burgers and set aside. Chop the remaining lettuce and put into a bowl with the dressing and croutons. Toss together to fully coat.
Serve burgers on buns topped with sliced tomatoes, lettuce leaves and condiments of choice.