Heat grill to high temperature. Form meat into 4 patties and season both sides with salt and pepper. Grill about 5 minutes on each side or until reached desired temperature. During the last minute of grilling, place a slice of the cheese on each patty, then close the lid and cook until the cheese has just melted, about 1 minute. Spread dressing evenly on buns. Place burgers on buns and top evenly with pastrami, onion, sauerkraut and lettuce. Serve with dill pickles, if desired.