Trim excess fat from the chicken and cut into 1-inch pieces. In a bowl combine cornstarch (3 tbs), all-purpose flour (2 tbs), egg (1), light soy sauce (1 tbs), garlic powder (1/2 tsp), black pepper (1/4 tsp) and salt (1/2 tsp). Add chicken pieces and mix thoroughly so each piece is coated. Cover and refrigerate for 15–30 minutes (minimum 15 minutes) to let the coating adhere.

Coating & Frying

Dust and Fry Chicken

Heat vegetable oil (3 cups) in a heavy-bottomed pot or deep fryer to 350°F (175°C). Place extra cornstarch (2 tbs) in a shallow dish. Remove chicken from marinade and lightly dust each piece in the extra cornstarch to remove excess wetness — this helps a crisp exterior. Fry chicken in batches (don't crowd) for 4–6 minutes per batch, until golden brown and cooked through (internal temperature 165°F/74°C). Drain on a wire rack or paper towels. Keep warm while you make the sauce.

Sauce & Stir-fry

Make Sauce

In a small bowl combine tomato ketchup (3 tbs), chili sauce (1.5 tbs), dark soy sauce (1 tbs), light soy sauce (1 tbs), rice vinegar (1 tbs), sugar (1 tsp), water (1/4 cup) and salt (1/4 tsp). Stir to dissolve sugar. Prepare cornstarch slurry by mixing 1 tsp cornstarch with 2 tsp water and set aside.

Stir-fry Aromatics and Vegetables

Heat 1 tbs vegetable oil in a large nonstick or wok over medium-high heat until shimmering. Add minced garlic (4 cloves) and minced ginger (1 tbs); stir-fry 15–20 seconds until fragrant but not browned. Add dried red chilies (6) and stir 10 seconds. Add onion pieces (1 each) and bell peppers (green 1, red 1/2) and stir-fry 1.5–2 minutes until vegetables are crisp-tender.

Combine Sauce and Chicken

Pour the prepared sauce into the wok and bring to a simmer. Add the cornstarch slurry and stir constantly for 30–60 seconds until the sauce thickens and becomes glossy. Add the fried chicken pieces and toss quickly to coat evenly in the sauce, cooking 1–2 minutes so chicken heats through and absorbs sauce. Add scallion greens (3 stalks sliced) and sesame oil (1/2 tsp), toss once more. Taste and adjust with a pinch more salt or pepper (1/4 tsp cracked black pepper) if needed.

Serve & Garnish

Transfer chilli chicken to a serving plate. Sprinkle toasted sesame seeds (1 tsp) and extra sliced scallions (2 stalks) if using. Serve immediately with steamed rice or fried rice, and offer extra chili sauce at the table.