- Heat grill to medium-high heat. Shape meat into 4 (1/2-inch-thick) patties. Place mushrooms and onions on sheet of foil; drizzle with oil.
- Grill patties 5 to 6 min. on each side or until done (160°F). Meanwhile, grill vegetables (on foil) 4 to 5 min. or until crisp-tender; remove from grill.
- Top burgers with cheese. Place rolls, cut-sides down, on grill. Cook 1 min. or until cheese is melted and buns are lightly toasted.
- Mix mayo, horseradish and chives; spread onto rolls. Fill with burgers and vegetables.
Kraft Kitchen's Tips
Serving Suggestion: Serve with a mixed green salad and your favorite fresh fruit to round out the meal.
Use a Grill Pan: If you have a grill pan, you can use that to grill the sliced vegetables instead of the foil, placing the grill pan on the grill grate before heating the grill. Then, use it to grill the vegetables as directed.
How to Cook on the Stove: Cook patties in large skillet on medium heat 5 min.; turn. Add mushrooms and onions to skillet; cook 4 to 5 min. or until burgers are done (160°F) and onions are crisp-tender, stirring vegetables after 3 min. Remove vegetables from skillet. Top burgers with cheese; cover. Cook 1 min. or until melted. Meanwhile, toast rolls under broiler, if desired. Spread rolls with mayo mixture, then fill as directed.