1/3 cup KRAFT Lite Zesty Italian Dressing, divided
1 lb. boneless beef sirloin steak, cut into thin slices
2 red peppers, sliced
1 small red onion, sliced, separated into rings
10 cups torn mixed salad greens
1/4 cup crumbled ATHENOS Blue Cheese
Heat 1 Tbsp. of the dressing in large skillet on medium-high heat. Add meat; cook 2 min., stirring constantly. Add peppers and onions; cook and stir 5 min. or until meat is cooked through and vegetables are crisp-tender. Stir in remaining dressing. Place 2-1/2 cups of the greens on each of four salad plates. Top evenly with the meat mixture and cheese just before serving.