HEAT grill to medium-high heat.
SHAPE meat into 4 (1/2-inch-thick) patties.
GRILL 4 to 6 min. on each side or until done (160 degrees F). Top with cheese; grill 1 min. or until melted. Meanwhile, place onions and buns, cut-sides down, on grill; cook 1 to 2 min. or until onions are lightly browned and buns are lightly toasted, turning onions after 1 min.
SPREAD mayonnaise onto cut sides of buns; fill with cheeseburgers and onions.
Serving Suggestion: Serve with a mixed green salad and your favorite fresh fruit to round out the meal.
How to Cook on the Stove: Cook patties in large skillet on medium heat 7 to 9 min. on each side or until done (160degreesF), adding onions to the skillet for the last 5 min. and turning once. Top burgers with cheese; cover. Cook 1 min. or until melted. Continue as directed, toasting buns under the broiler if desired.
Substitute: Substitute kaiser rolls for the hamburger buns.