In a large bowl, combine the chicken thighs with soy sauce and 2 tablespoons of cornstarch. Mix well and marinate for 30 minutes.

In a separate bowl, mix lemon juice, sugar, water, 2 teaspoons of cornstarch, and lemon zest until sugar and cornstarch are dissolved.

Coat the marinated chicken with flour and remaining cornstarch, ensuring each piece is evenly coated.

Heat oil in a deep skillet to 350°F. Use a thermometer for accuracy.

Fry marinated and coated chicken pieces in batches for 4-5 minutes until golden brown.

Transfer fried chicken to a skillet, pour in sauce, and cook on low heat for 2-3 minutes until sauce thickens.

Serve immediately with steamed rice and vegetables.