HEAT oven to 425°F.
CRUMPLE 4 sheets of foil to make 4 (3-inch) balls; place on baking sheet. Top each with 1 tortilla; spray with cooking spray. Bake 6 to 8 min. or until tortillas are golden brown. (Tortillas will drape over balls as they bake to form shells.)
MEANWHILE, brown meat with chili powder in large nonstick skillet. Stir in beans and salsa; cook 3 to 5 min. or until heated through, stirring occasionally.
FILL tortilla shells with salad greens, meat mixture, cheese and tomatoes. Drizzle with dressing.