Place chicken, 1 tablespoon of soy sauce, and 1 tablespoon of cornstarch in a bowl, and mix to combine.
In another small bowl, combine remaining soy sauce, cornstarch, oyster sauce, water, and brown sugar to make the Kung Pao sauce.
Heat oil in a saucepan and sauté the coated chicken for 6-7 minutes until golden.
Then toss in the bell pepper, garlic, and ginger and cook about 5 minutes, until the bell pepper is just softened.
Add in the Kung Pao sauce, bring to a simmer, stirring constantly, and cook for about 3-4 minutes, until the sauce has thickened.
Next, add the peanuts and green onion and cook for about 4 more minutes.
Serve the kung pao chicken over rice or noodles.