Heat 1 tbsp oil in a wok. Stir-fry chicken for 6 minutes until browned, remove and set aside.
Add remaining oil, stir-fry peppers, onions, and mangetout for 4 minutes. Add garlic and ginger, cook 1 minute.
Return chicken, stir in sweet chilli sauce, soy sauce, fish sauce (if using), cornflour slurry, and lime juice. Toss well and cook until thickened and glossy.
Serve hot with steamed rice.
Note
Add fresh chilli for heat, skip fish sauce to reduce sodium.