I absolutely love stir fry's. So many good flavours and textures all in one bowl! Found the best sauce in an old book by Rose Reisman.
What I did was saute all of my veggies in the wok and I started with onion and then added peppers, asparagus and spinach. Once they were all ready to serve I poured on this sauce...and served over brown rice.
2T soya sauce; 2T hoisin sauce; 2T rice vinegar; 1T brown sugar; 1T veg oil; 1/2t minced fresh ginger; 1/2 t crushed garlic. Mix them all well in a jar and use when ready!