Whisk together egg white, soy sauce, chicken broth, cornstarch, baking soda, and salt in a medium bowl and marinate chicken pieces for 15 minutes.
Mix flour, cornstarch, baking powder, and salt in a separate bowl and dredge the marinated chicken pieces in this dry coating until fully covered.
Heat 2 inches of oil to 350°F (175°C) in a deep skillet or pot and fry the coated chicken in batches until golden and crispy, about 3–4 minutes per batch. Drain on paper towels.
In a large skillet or wok, heat 1 teaspoon oil over medium heat and cook minced ginger and garlic until fragrant, about 30 seconds.
Add orange zest, orange juice, soy sauce, vinegar, chicken broth, and sugar to the skillet and simmer for 2–3 minutes until sauce thickens slightly. Stir in sesame oil.
Toss fried chicken gently in the orange sauce until evenly coated with the glossy glaze.
Serve the orange chicken over warm cooked noodles, spoon extra sauce over top, garnish with sliced scallions, and add optional steamed vegetables.