Toss shrimp gently with soy sauce. Cover and refrigerate until ready to cook. Mix cornstarch with an equal amount of cold water and set aside.
Combine sauce ingredients and set aside.
Lightly spray a large non-stick skillet with cooking spray and preheat over medium-high for 2 minutes. Add shrimp, garlic and ginger and stir-fry until shrimp turn bright pink, about 2 minutes. Transfer shrimp to a large plate or platter.
Reduce heat to medium and saute pepper and onion until onions begin to separate and pepper brightens, about 2 minutes.
Increase heat to medium-high and return shrimp to pan. Stirring, add sauce to shrimp and bring to low boil. Stirring constantly, add cornstarch/water mixture. After sauce has thickened, about 60 seconds; reduce heat to low. Taste and adjust seasonings if necessary; remove from heat and serve over rice.