Heat grill to medium heat.
Blend steak sauce, chiles, water and 1 garlic clove in blender until smooth. Strain; set aside.
Chop remaining garlic. Add to meat and onions in large bowl; mix lightly. Shape into 8 (3/4-inch-thick) patties. Grill, covered, 5 to 7 min. on each side or until done (160ºF). Top with Singles. Grill 1 min. or until Singles begin to melt.
Spread bottom halves of buns with mayo; fill with lettuce, tomatoes, burgers and sauce mixture.