Preheat oven to 200C or 180C fan-forced. Place rolls on a tray and bake, according to directions on packet.
Meanwhile, heat a chargrill or frying pan on high and spray with oil. Cook beef patties for 2-3 mins each side, or until cooked through.
Split rolls in half. Top base of each roll with lettuce, beef patty, tomato and a dollop of guacamole. Season with cracked pepper. Finish with top of roll and serve with barbecue sauce.