1.Place chicken in a shallow baking dish. In a jug, combine vinegar, sugar and garlic with half the oil. Pour over chicken, turning to coat. Cover with plastic wrap and chill for 10 minutes.
2.Heat the remaining oil in a non-stick frying pan on medium. Cook chicken, basting occasionally with marinade, for 2-3 minutes each side, until cooked through. Transfer to a plate, cover with foil and rest for 5 minutes.
3.Meanwhile, cook spinach and tomato in same frying pan on medium for 1-2 minutes until spinach wilts. Remove from heat.
4.Toss chicken through spinach mixture. Top the noodles with chicken and vegetable mixture and drizzle with pan juices to serve.