COVER rimmed baking sheet with foil; spray with cooking spray. Place first 5 ingredients on baking sheet. Broil, 4 inches from heat, 12 min. or until roasted, turning every 5 min. and removing ingredients from pan when tortillas are crisp and vegetables are roasted to desired doneness.
MEANWHILE, cook and stir bacon in large deep ovenproof skillet or Dutch oven until crisp. Remove bacon from skillet with slotted spoon; drain on paper towels. Discard all but 1 Tbsp. drippings from skillet. Add pork loin to drippings in skillet; cook 5 min. or until evenly browned, turning after 3 min.
HEAT oven to 350ºF. Blend broth, tortillas and all roasted vegetables except chiles in blender until smooth. Add to pork loin in skillet; cover. Bake 1-1/2 hours or until done (145ºF). Meanwhile, toss potatoes, chayotes and beans with dressing; spread onto foil-covered rimmed baking sheet sprayed with cooking spray. Cover; bake 1 hour 15 min., uncovering after 45 min.
REMOVE about 1/3 of the tomatillo sauce from skillet; blend in blender with roasted serrano chile until smooth. Pour into serving bowl. Spoon remaining sauce onto platter; top with pork loin. Surround with baked vegetables; sprinkle with bacon.