Begin by cutting the chicken into small bite-sized pieces.

In a mixing bowl, combine the chicken pieces with grated ginger, garlic, and crushed chili flakes (if using). Set aside to marinate.

Prepare the orange sauce by mixing together orange juice, light soy sauce, brown sugar, chicken stock, corn starch, and sesame oil in a small bowl.

In a large mixing bowl, whisk together the egg, corn flour, and water to create a thick batter.

Add the marinated chicken pieces to the batter, ensuring each piece is well-coated.

Heat oil in a deep frying pan or pot to 350°F (175°C).

Carefully lower the battered chicken pieces into the oil and fry them in batches until crispy and golden brown.

Remove from oil and transfer to a cooling rack or a plate lined with paper towel.

In a large wok or pan, heat vegetable oil over medium heat and sauté chopped ginger and garlic until fragrant.

Stir in the prepared orange sauce, stirring continuously until it reduces and thickens.

Add the crispy chicken pieces to the sauce, mixing well to coat evenly. Finish with orange zest.

Transfer to a serving plate and garnish with chopped spring onions and toasted sesame seeds.

Serve immediately.