In a medium bowl, whisk together the orange zest, orange juice, soy sauce, water, rice vinegar, cornstarch, sesame oil, and sugar until smooth and well combined. Set aside while preparing the chicken. The mixture will thicken once heated.

In a large bowl, whisk the eggs with salt and pepper. Add the cubed chicken and toss until evenly coated. In a separate shallow dish, combine cornstarch and flour. Using tongs, remove each piece of chicken from the egg mixture, allowing excess liquid to drip off, and dredge it thoroughly in the cornstarch-flour mixture until fully coated. Place on a clean plate.

In a large deep skillet or wok, heat the vegetable oil over medium-high heat until it reaches approximately 350°F (175°C). To test without a thermometer, sprinkle in a pinch of flour — if it sizzles immediately, the oil is ready. Fry the chicken in batches, ensuring not to overcrowd the pan. Cook for 3–4 minutes per side, or until the chicken is golden brown and cooked through. Transfer to a paper towel-lined plate to drain excess oil. Repeat until all chicken pieces are fried.

Once all the chicken has been fried, carefully discard the used oil and wipe the skillet clean. Add 1 tablespoon of fresh oil to the skillet. Add the chopped garlic and shallot and sauté over medium heat for 1–2 minutes, until fragrant and lightly golden.

Pour the prepared orange sauce into the skillet with the aromatics. Bring to a gentle simmer and cook until the sauce begins to thicken and develop a glossy texture, about 3–5 minutes. Once thickened, return the fried chicken to the skillet and toss well to coat each piece evenly in the sauce. Continue simmering for 1–2 minutes to allow the chicken to absorb the flavors.

Transfer the Chinese Orange Chicken to a serving platter or individual plates. Garnish with sliced scallions and toasted sesame seeds. Serve immediately over steamed white rice or alongside stir-fried vegetables for a complete meal.