
Combine all the marinade ingredients in a medium-sized bowl and mix well. Let sit for 10 minutes while preparing the rest of the ingredients.
Mix the sauce ingredients together in a small bowl.
Heat butter in a large nonstick pan over medium-high heat until hot. Add garlic and ginger. Stir and cook for a few seconds to release the fragrance.
Add the shrimp. Cook and stir occasionally, until both sides turn golden.
Add the sauce. Cook and stir until it thickens slightly, 1 minute or so. Add the green onion if using and stir to mix well. Immediately transfer everything to a plate. Serve hot over steamed rice as a main.