Have plenty of mayonnaise and mustard on hand for these tasty burgers. Serve with corn on the cob and potato salad and a chilled Brennan's Amber.
Mix first 4 ingredients in large bowl until blended. Mix in pepper. Shape the meat mixture into eight- inch thick patties. (Can be made 8 hours ahead. Cover and chill.)
Prepare barbecue (medium-high heat). Grill patties to desired doneness, topping with cheese for last minute of cooking, about 6 minutes per side for medium-rare1-inch thick patties. Place burgers on bottom halves of buns. Top with lettuce, tomatoes and upper halves of buns.