1. To make the marinade whisk the hoisin sauce, vinegar, soy sauce, sugar, cornstarch, and water in a bowl.  Place the cut up chicken into the mixture, stir to coat, and then cover and refrigerated for at least 30 minutes.

2.  After the chicken is done marinating, heat 1 tablespoon of peanut oil in a large skillet over medium heat until hot.  Sauté the garlic, ginger and red pepper flakes until fragrant.  Add 2 cups of the hoisin marinade to the skillet and simmer, whisking constantly, until the mixture is dark brown and thickened.  Remove from heat, cover and keep the sauce warm on low heat.

3.  Whisk the egg whites in a shallow dish until foamy; set aside.  Combine the cornstarch, flour, baking soda, and remaining hoisin marinade in a second shallow dish; mix until it resembles coarse meal.

4.  Remove the chicken from the marinade (I put mine into a colander and let the marinade drain).  Coat the chicken in batches in the foamy egg whites until well coated, then cover the chicken in the cornstarch mixture, pressing to adhere.

5. Heat the oil in a skillet over medium high heat until hot.  Cook the chicken on all sides until it is browned and cook through.  Place the cooked chicken on a paper towel to remove excess oil, and then place into the warm sauce.  Repeat with remaining chicken.

6.  Stir the sauce and chicken together and bring up to a higher heat to make sure that the sauce and chicken are hot.  Serve with rice and garnish with green onions.