Begin by cutting the chicken breast or thighs into bite-sized pieces for quick cooking. In a bowl, mix the chicken with soy sauce, Shaoxing wine (if using), and 1 tablespoon of cornstarch. Ensure all pieces are evenly coated, then cover and let marinate for 30 minutes in the refrigerator.

While the chicken is marinating, combine cornstarch and all-purpose flour in a shallow dish. Stir well to ensure the dry ingredients are evenly blended. Set it aside, ready for when the chicken is fully marinated.

In a large wok or deep frying pan, pour in about two inches of vegetable or canola oil. Heat the oil over medium-high heat until it reaches around 350°F (175°C).

Once the oil is hot, carefully coat each marinated chicken piece in the cornstarch-flour mixture, then deep-fry in small batches, for about 3-4 minutes or until golden brown and crispy. Transfer to a paper towel-lined plate.

While the chicken is frying, combine lemon juice, sugar, water, 1 tablespoon of cornstarch, and a pinch of salt in a small saucepan. Stir and bring to a boil, then keep stirring until the sauce thickens, about 3-5 minutes.

Once the chicken is fried, transfer it to a large bowl and pour the hot lemon sauce over the chicken, tossing gently to coat evenly. Serve immediately, garnished with sesame seeds.