Wipe out skillet; heat oil in skillet over medium heat. Add zucchini; cook 2 minutes, turning frequently with tongs. Add beef mixture, tomatoes, taco seasoning mix, salt and pepper flakes. Stir to completely coat noodles; cook 1 to 2 minutes or until completely heated through. Stir in 1 cup of the cheese. Top with remaining 1/2 cup cheese and the cilantro. Serve immediately.