Prepare the Chicken: Cut the chicken thighs into bite-sized pieces suitable for frying.
Marinate the Chicken: In a mixing bowl, combine chicken pieces with soy sauce, Shaoxing wine, minced ginger, minced garlic, white pepper, and egg white. Mix well to ensure each piece is evenly coated. Allow to marinate.
Coat with Sweet Potato Flour: Dredge the marinated chicken pieces in thick sweet potato flour until well coated.
Fry the Chicken: Heat oil in a deep fryer or a deep pan to 375°F (190°C). Fry the chicken pieces until golden brown and crispy, about 5-6 minutes. Do not overcrowd the pan.
Fry the Basil Leaves: In the last 30 seconds of frying, add the fresh basil leaves to the oil to crisp up.
Season: Mix together white pepper, salt, five-spice powder, and sugar in a small bowl. Once the chicken and basil are fried and drained, sprinkle the seasoning mix over them while still hot.