Over a medium high to high heat, add oil to skillet. Add pork tenderloin to skillet and cook until lightly browned all over. I cover skillet so pork cooks through better and grease doesn’t spray all over the stove. Remove any excess oil, but leave meat in the pan.

Add the chopped onion, peppers and celery and stir fry for a couple of minutes. Do not brown vegetables (they may have a brown color to them due to the fond in the pan from the pork, which is OK). Add 3-4 Tbsp soy sauce. Cook over low to medium heat, until vegetables are cooked but still crisp. In a separate combine bowl or cup, combine cornstarch, soy sauce, and about 1/4 to a 1/2 cup water. Stir to combine.

Add cornstarch mixture to vegetables. Cook on medium heat until thickened, stirring occasionally. Add the bean sprouts and heat throughout.

If mixture is too thick, thin with a little water. Not thick enough, add a little more cornstarch mixed with water to the mixture.

Serve on hamburger rolls, over chow mein noodles, white rice or all by itself.