Cut chicken or vegan substitute into 1 inch pieces.
In a medium bowl mix together flour, corn starch, salt and pepper. Add in egg (or egg replacer), oil, water. Whisk until combined.
Add chicken to the mixture and coat. Chill in the fridge for 20 minutes.
In a large to medium saucepan add 2 inches of vegetable oil, heat to 350 F and add marinated chicken, 10-15 pieces at a time to the oil and deep fry for 3 minutes turning half way for even cooking.
Remove from pan onto a paper towel lined plate and cover with foil to keep warm while you prepare the sauce.
In a medium saucepan add orange juice, orange zest, soy sauce, rice vinegar, garlic and brown sugar. Place saucepan over medium heat and bring to a low boil.
Mix in corn starch and water and stir until the sauce thickens. About 1-3 minutes.
Add in fried chicken and toss until evenly coated.
Garnish with sesame seeds and serve with this fried rice and these vegetable spring rolls.