Begin by cutting boneless chicken thighs into bite-sized pieces and placing them in a mixing bowl. Add soy sauce, sesame oil, garlic paste, and baking soda, ensuring all the chicken is coated well. Allow the chicken to marinate for at least 15 minutes.

While the chicken marinates, wash and slice the sweet onion, green pepper, and fresh red chilies. Halve the dry red chilies and remove the seeds for a balanced heat level.

In a small bowl, combine salt, black pepper, Chinese five spices, and chicken powder (if using). Set this mixture aside for easy access during cooking.

Sprinkle corn starch over the marinated chicken, tossing gently to coat each piece thoroughly. Discard any excess corn starch.

In a deep frying pan, heat oil to a temperature of 350°F (175°C). Carefully add the coated chicken pieces in batches, frying them for about 6-8 minutes or until they are golden brown and crispy. Use a slotted spoon to remove the chicken from the oil.

In a wok, heat 1 tablespoon of oil over medium-high heat. Quickly stir-fry minced garlic for about 30 seconds, then add the dry red chilies, crushed chilies, sliced onions, and green peppers, cooking for another minute.

Add the crispy chicken back into the wok, then sprinkle the prepared spice mix all over. Toss everything together for about 1-2 minutes.

Once combined, remove the wok from heat and transfer the crispy salt and chilli chicken to a serving dish.