Add the turkey and stir-fry briskly for 3-4 minutes. Add the spring onions, pepper, carrot, celery and mushrooms. Stir-fry over a high heat for another 3-4 minutes, until the turkey is cooked. The vegetables should remain crisp and crunchy.
For a vegetarian version, replace the turkey with a 300g pack of firm tofu cut into chunks, or Quorn chicken-style pieces.
Give the orange juice mixture a good stir, then add it to the stir-fry and cook for a few moments until thickened. Drain the noodles well, then add them to the turkey mixture. Serve at once.