In a bowl, whisk together marinade ingredients, except water and cornstarch.  Add 1/3 of marinade to the shrimp.  Marinate, and let stand at room temperature while you prep the vegetables. 

     To the remaining marinade, whisk in ¼ c. water and cornstarch.

            Meanwhile, in a large skillet, heat oil over medium-high.  Add onions, peppers, garlic and ginger and sauté 3-4 minutes.  Add shrimp and stir fry just until opaque, about 2-3 minutes.  Add remaining marinade to skillet and simmer until marinade thickens, 2-3 minutes. 

     Serve with noodles or rice.