Trim off fat from chicken. Slice into ¼ inch pieces. Season with salt, white pepper, and garlic powder. Set aside and marinade for at least 30 minutes.
In a large bowl, combine cornstarch, flour, baking powder, and water. Whisk together until smooth and thick consistency.
Add marinated chicken to the batter. Mix well until chicken is evenly coated.
In a bowl, mix together, water, orange juice, orange concentrate, sugar, soy sauce, and dark soy sauce.
In a large wok, heat oil to 350°F. Fry battered chicken for 3-4 minutes or until the batter is firm and is a pale beige color. Remove from oil and strain. Let it cool. (You can store this in the fridge for up to one week)
When ready to cook, fry par fried chicken for another 2-3 minutes at 400°F or until batter turns lightly golden.
In a pan heat as much sauce mixture as you need. (I usually do half at a time) Once sauce is boiling, add cornstarch slurry to thicken.
Add double fried chicken pieces, toss well and until everything is evenly coated. Serve hot and enjoy!