Cut the chicken into bite sized pieces. In a large bowl, toss the chicken with cornstarch until all pieces are well coated.
Heat 1 tablespoon of the vegetable oil in a large skillet or wok on medium high. When the oil starts to shimmer, quickly cook the chicken in batches until golden brown. Set the cooked pieces aside.
Add more oil to the pan after each batch, and repeat until all chicken is cooked.
In a medium bowl, combine the chili sauce, hoisin sauce, soy sauce, garlic, ginger, pepper and water. Whisk until well combined.
Reduce heat to medium and return chicken to the skillet. Pour the sauce over the chicken. Cook to heat through, then reduce to low and simmer for 10 to 15 minutes until the chicken is tender and the sauce has thickened.
Stir in the green onions, and cook an additional 5 minutes.
Serve hot over cooked rice with steamed vegetables.