For the chicken: In a large bowl, whisk together the cornstarch and egg whites with a fork until almost frothy, about 1 minute. Add the chicken to the mixture and allow to sit for 5 to 10 minutes.
For the sauce: Meanwhile, put the orange juice, soy sauce, sugar, vinegar, sesame oil, salt, crushed red pepper, garlic and ginger in a small nonstick skillet and whisk. Heat until bubbling and starting to thicken, about 5 minutes.
Whisk together the cornstarch and 1/4 cup water in a small bowl and add 1 to 2 tablespoons of the cornstarch slurry to the sauce. Mix in and thicken for 1 minute.
Heat about 2 inches of vegetable oil in a heavy-bottomed Dutch oven until a deep-fry thermometer inserted in the oil registers 350 degrees F. Carefully drop the chicken into the oil and move it around, flipping gently, until golden, 3 to 4 minutes. Let the pieces drain on a plate lined with paper towels for 2 to 3 minutes. Then drop them back into the oil for 1 minute to really solidify the coating.