Prepare the Chicken: Combine the chicken pieces with salt, sugar, white pepper powder, minced garlic, and rice wine or mirin. Let it marinate for about 10 minutes.
Make the Seasoning: In a small bowl, mix together salt, sugar, garlic powder, black pepper powder, and white pepper powder. Keep aside.
Make the Batter: In a bowl, mix together the cornstarch, all-purpose flour, baking soda, water, and vegetable oil until smooth.
Add the marinated chicken into the batter. Keep aside.
First Fry: Heat the oil in a pan to 350°F (175°C).
Fry the chicken pieces until they are light golden brown, but not fully cooked, about 3 minutes. Adjust the heat as needed since adding new pieces will lower the oil temperature. You might need to cook the chicken in batches.
Remove the chicken pieces from the oil and let them rest on a paper towel-lined plate for 10 minutes.
Second Fry: Increase the heat of the oil to 380°F (195°C).
Fry the chicken pieces again until they are crispy and deep golden brown, about 1 minute.
Remove from the oil and let them rest on a paper towel-lined plate to drain excess oil.
Stir-Fry Aromatics: Heat 2 tablespoons of oil in a wok or large skillet. Add the garlic and jalapeño, and cook 1-2 minutes.
Add the green onions. Stir-fry further for 30 seconds.
Combine and Serve: Add the double-fried chicken to the wok with the aromatics. Sprinkle with the salt and pepper seasoning. Toss everything together until well coated and heated through. Serve immediately.
Enjoy!