To marinate the chicken, in a bowl, mix the chicken with the salt until absorbed, then add the white pepper and rice wine and mix well, then add the cornstarch mixed with water and the egg white and mix thoroughly, then let marinate while preparing the remaining ingredients.
To make the sauce, in a bowl, mix the orange juice, soy sauce, ketchup, rice vinegar, sugar, and orange zest until combined.
To make the batter, in a bowl, mix the cornstarch, baking soda, baking powder, salt, egg, cooking oil, and water until smooth, then add the chicken and coat evenly.
To first fry, in a pot over high heat, heat the cooking oil to 350°F (177°C), then fry the chicken in batches for about 4–5 minutes until lightly golden and cooked through, then remove and drain.
To second fry, increase the oil temperature to 375°F (191°C), return the chicken, and fry for about 1 minute until golden and crispy, then remove and drain well.
To make the sauce glossy, in a pan over medium heat, bring the sauce to a simmer, then add the cornstarch mixed with water and cook until thickened and glossy.
To finish, add the chicken to the sauce and toss to coat, then garnish with the scallions and orange slices.