1. Prepare the Batter & Fry the Chicken:

1. In a bowl, season the chicken with salt and pepper.
2. In a separate bowl, mix cornstarch and beaten egg until a thick paste forms. Toss the chicken pieces in this mixture.
3. In another bowl, whisk together flour, baking powder, and water to make a smooth batter.
4. Heat oil in a deep pan or wok to 350°F (175°C).
5. Dip the coated chicken pieces into the batter, then fry until golden brown and crispy (about 4-5 minutes per batch). Drain on a paper towel.

2. Make the Lemon Sauce:

1. In a small saucepan over medium heat, combine lemon juice, sugar, honey, soy sauce, garlic, and ginger. Stir well.
2. Once the mixture starts to simmer, add the cornstarch slurry and stir until the sauce thickens (about 2 minutes).
3. Stir in the lemon zest and remove from heat.

3. Assemble the Dish:

1. Pour the lemon sauce over the crispy chicken and toss gently to coat.
2. Garnish with sesame seeds, chopped green onions, and lemon slices.
3. Serve immediately with steamed rice or noodles.