Combine chicken, sauce, ginger and garlic in a medium bowl.
Place noodles in a large heatproof bowl, cover with boiling water; stand until tender, drain.
Heat remaining oil in wok; stir-fry chicken, in batches, until browned. Remove from wok.
Heat remaining oil in wok; stir-fry beans and mushrooms until tender. Return chicken to wok with the noodles, water and paste; stir-fry until hot. Add spinach; stir-fry until spinach wilts, season to taste.