Grill 13 to 15 min. or until peppers are crisp-tender and steaks are cooked to medium doneness (160ºF), turning after 7 min. Remove peppers and steaks from barbecue; let stand 3 min. Meanwhile, grill tortillas 1 min. or just until warmed and lightly browned on bottoms; turn. Top with Kraft Singles
; grill 1 min. or until melted. Remove from barbecue.