Photograph: Karen Thomas
Heat the oil in a large deep pan or casserole over a high heat. Add the chicken pieces and fry for 10 minutes, turning often, until they're browned. Transfer to a plate. Lower the heat and add the red onion, ginger and lemongrass. Gently fry for 6-8 minutes until softened.
Return the chicken to the pan, add the curry powder and garlic, stirring until the chicken is well coated. Add the stock, coconut milk, potatoes and carrots; stir. Bring to the boil, cover and simmer gently for 15 minutes.
Season with the fish sauce, sugar and a pinch of black pepper; add the okra, aubergine and shallots. Cook, covered, for 10 minutes.
Remove the lid, stir in the mangetout; simmer for a further 5 minutes. Serve sprinkled with the basil, spring onion and chillies.
Get ahead: make up to the end of step 3 a day ahead; chill.
This recipe is adapted from My Vietnamese Kitchen by Uyen Luu (Ryland Peters & Small, £16.99)