In a large bowl, combine the cornstarch, egg, soy sauce, salt and pepper. Mix the chicken so it is well coated.
Heat oil in a large skillet or wok over medium-high heat. Cook the chicken for about 6 minutes or until golden brown. Remove chicken and set aside. Keep 1 tablespoon of oil.
In small bowl, add the tomato puree, chili garlic sauce, water, soy sauce, cornstarch, vinegar and sugar and whisk until the cornstarch is dissolved. Set aside.
With the oil at medium heat, add the garlic and ginger, cooking for 30 seconds. Add the green onions and pepper, cooking for another 2 minutes. Pour in the sauce, cooking until it thickens, about 1 minute.
Toss in the chicken until it is coated and warmed through. Serve over rice and top with additional green onions.
Notes
Be consistent with the size you cut the chicken so it cooks evenly.
You can let the chicken marinate in the egg/cornstarch mixture for an hour as it helps tenderize the chicken even more. I skip this step since I use chicken thighs.
Cook the chicken in batches so you don't overload the wok and cool it down. You want to cook the chicken quickly and adding too much at a time will slow the cooking process.
If you want more heat, add crushed red pepper flakes in ½ teaspoon increments on increase the amount of chili garlic sauce.
Feel free to customize this dish by adding other ingredients like cashews, sesame seeds, or your favorite vegetables.