1. Tear one hamburger bun into pieces. Place in food processor or blender container. Cover; pulse on and off, to form fine crumbs.
2. Combine ground beef, bread crumbs, onion, egg white, garlic, salt and pepper in medium bowl, mixing lightly but thoroughly. Lightly shape into eight 1/2-inch thick mini patties.
3. Place patties on grill over medium, ash-covered coals. Grill, covered, 8 to 9 minutes (over medium heat on preheated gas grill, 9 to 10 minutes) until instant-read thermometer inserted horizontally into center registers 160 degrees F, turning occasionally. About 1-1/2 minutes before burgers are done, place rolls, cut sides down, on grid. Grill until lightly toasted.
4. Serve burgers in buns with topping as desired Topping(s) Variation(s). Close sandwiches.