In a bowl combine chicken pieces with ginger-garlic paste (1 tbs), light soy sauce (1 tbs), kosher salt (1 tsp) and black pepper (1/2 tsp). Mix well, cover and let rest for 15-20 minutes in the refrigerator.

Set up coating

In a shallow bowl whisk the egg. In a separate large bowl combine cornstarch (1 cup), all-purpose flour (1/2 cup) and red chili powder (1/2 tsp).

Coat chicken

Toss marinated chicken briefly in the egg, then dredge in the cornstarch-flour mixture, pressing lightly so the coating adheres evenly. Shake off excess.

Heat oil

Pour 600 ml vegetable oil into a heavy-bottomed pan or wok and heat over medium-high until it reaches 350°F (175°C) or until a small piece of coating sizzles and rises steadily.

Fry chicken

Fry the coated pieces in batches (do not overcrowd) for 4-6 minutes per batch until golden brown and cooked through. Remove with a slotted spoon and drain on a wire rack or paper towels. For extra-crisp texture, fry a second time at 375°F (190°C) for 1-2 minutes, then drain.

For the sauce and vegetables

Prepare vegetables

While chicken is resting, slice garlic thinly, julienne ginger, slit green chilies, cut onion and bell peppers into 1-inch pieces, and slice spring onions separating whites and greens.

Combine sauce ingredients

In a small bowl whisk together tomato ketchup (3 tbs), chili sauce (1.5 tbs), dark soy sauce (1 tsp), light soy sauce (1 tbs), rice vinegar (1 tsp), brown sugar (1 tsp), salt (1/2 tsp) and black pepper (1/4 tsp). In another small bowl make a slurry by dissolving 1 tsp cornstarch in 3 tbs water.

Stir-fry aromatics and veg

Heat 2 tbs vegetable oil in a large wok or heavy skillet over high heat until shimmering. Add sliced garlic and julienned ginger; stir-fry 20-30 seconds until fragrant but not browned. Add the white parts of the spring onion and green chilies; stir 15 seconds. Add onion and bell peppers and stir-fry 1-2 minutes — vegetables should be crisp-tender.

Add sauces and thicken

Reduce heat to medium-high. Pour the prepared sauce mixture into the wok, stirring to combine. Bring to a simmer, then add the cornstarch slurry while stirring constantly. Cook 30-45 seconds until sauce thickens to a glossy coating.

Finish with sesame oil

Turn off heat, stir in 1/2 tsp sesame oil for aroma.

To finish and serve

Toss chicken in sauce

Add the fried chicken pieces to the wok with the sauce and vegetables. Toss quickly but gently over medium heat for 30-45 seconds until every piece is evenly coated and heated through. Do not over-stir to preserve crispness.

Garnish and serve

Transfer chilli chicken to a serving plate. Sprinkle chopped spring onion greens and sesame seeds over the top. Serve immediately with lemon wedges on the side for squeezing and steamed rice or fried rice/noodles as desired.