Combine chicken, egg white and 2 teaspoons cornstarch in small bowl. Let stand 20 minutes.
Meanwhile, combine water and 2 teaspoons cornstarch and mix into a slurry. Mix together black bean sauce, hoisin sauce, rice vinegar, sherry, sugar, garlic and red pepper flakes in another small bowl. Whisk cornstarch slurry into sauce and set aside.
Heat oil in wok or heavy large skillet over medium-high heat. If using raw peanuts, cook peanuts until they are golden brown; about 1 minute. Remove with slotted spoon and set aside.
Increase heat to high. Add chicken mixture and stir fry until chicken is lightly browned, about 1 to 1 1/2 minutes. Remove chicken to a bowl.
Reduce heat to medium and stir fry bell pepper and onions for 1 to 2 minutes.
Add peanuts and chicken to wok. Add sauce and blend thoroughly. Cook until heated through, about 1 to 1 1/2 minutes.
Serve immediately over freshly cooked rice.