For the marinade: mix broth, juice, zest vinegar, soy sauce, sugar, garlic, ginger and cayenne pepper in a large bowl. Measure out 3/4 cup of marinade and pour over chicken pieces. Set aside for 30 to 60 minutes.
While chicken is marinating, place remaining 1 1/2 cups marinade in a medium saucepan and bring to a boil. In a small bowl, stir together cold water and cornstarch.
Whisk cornstarch mixture into sauce and reduce heat to a simmer. Stir occasionally until sauce is thick and translucent, about 1 minute. Remove from heat and add chiles and orange peel.
For the coating:
In one pie plate, whisk egg whites. In a second pie plate mix cornstarch, 1/2 teaspoon cayenne and 1/2 teaspoon baking soda.
Drain the chicken and discard marinade. Pat chicken dry with paper towels.
Dip each chicken piece in egg whites and then in cornstarch mixture. Set chicken on wire rack until ready to fry.
To fry the chicken:
Heat oil in a large Dutch oven, fry baby or electric skillet to 350 degrees F. (Use a clip on thermometer if you don't have an electric fryer.)
Carefully place chicken pieces in hot oil, one piece at a time, and fry until golden brown, about 2-3 minutes per side, frying about 1/4 of the chicken at a time.
Drain pieces on a paper towel lined platter or baking sheet.
Reheat orange sauce over medium heat until simmering. Add chicken and gently toss until even coated and heated through. Serve immediately.