For the marinade, combine egg white, rice vinegar and corn starch in a medium size bowl. Stir to dissolve corn starch.
Add chicken and stir to coat. Allow to marinate for 20 minutes, then drain any liquid that may have accumulated.
Combine all sauce ingredients and whisk well to dissolve corn starch. Set aside.
Heat 2 tablespoons of coconut oil in a large skillet till hot and just starting to smoke. Add chicken to skillet and stir-fry for 4-6 minutes or until most of the chicken has turned white and opaque. It's okay to have a few areas that are still pink. It will finish cooking in the sauce. You don't want to overcook it.
Add orange sauce mixture and bring to a boil. Reduce to a low simmer and cook, uncovered, for 2-3 minutes till sauce has thickened.
Garnish with sesame seeds and finely chopped cilantro or parsley.