Combine first 8 ingredients. Shape into 8 (4-ounce) patties.
Grill patties, covered with grill lid, over medium-high heat (350° to 400°) 5 minutes on each side or until beef is no longer pink.
Spray cut sides of buns with cooking spray; place buns, cut sides down, on cooking grate, and grill 2 minutes or until lightly browned. Serve hamburgers on buns with desired toppings and Tomato-Basil Mayonnaise.