Add pork, soy sauce, and cornstarch in a large bowl. Mix properly, and let it rest for 30 minutes.
In a small bowl, add soy sauce, water, vinegar, sugar, sherry, cornstarch, and sesame oil. Mix them accordingly to make the sauce. Set it aside.
In a pot, add oil to heat and fry marinated pork until it will turn brown. Remove everything but save 3 tablespoons oil.
In a wok, add the remaining oil and add onion, mushrooms, broccoli, carrot, bell peppers, and celery to it. Also, add garlic, fried pork, peanuts, and chilies. Cook it for 5 minutes.
Drizzle the sauce over the pork and fry until it becomes thick.
Serve the Kung Pao pork with rice.