Put the sliced meat in a bowl and add soy sauce, garlic, and ground ginger. Let it marinate while you cut the vegetables into bite-sized pieces. Set aside the cut vegetables.
Heat oil in a large skillet until hot. Add the meat and stir-fry until nicely browned turn heat to low cover and continue to cook until meat is tender, stirring occasionally (don’t let it burn or dry out). Add the onion and Bell peppers. Cover and continue cooking until the vegetables are done.
Combine cornstarch and Hot water, add to stir-fry and boil until it thickens.