PLACE tomatoes in single layer on bottom of parchment-lined sheet pan. Bake in 400ºF convection oven 20 min. or until lightly charred.
MEANWHILE, grill corn on high heat 12 min. or until tender and lightly charred on all sides, turning occasionally.
FOR each serving: Grill 1 ground beef patty to medium (160ºF), or desired doneness. Brush with 2 Tbsp. barbecue sauce. Place on 1 toast slice; top with 3 roasted tomato slices, 1 pepper, 2 cheese slices and 2 Tbsp. lettuce. Cover with second toast slice. Serve with 1 ear of grilled corn.