For curry paste, blend garlic, shallots and ginger in a food processor. Add trimmed and cut up lemongrass , chilli, cumin and half the coriander to the processor. Blend till it forms a paste.
Cut up chicken into bitesize pieces and fry for 5 to 7 mins in a large pan with 1 tablespoon of cooking oil. Set to one side.
Cut the mushrooms and fry for 4 to 5 minutes, or until golden. Transfer to a plate using a slotted spoon.
On a medium-low heat, add the Thai green paste for 4 to 5 minutes, stirring occasionally. Pour in the coconut milk, 400ml of boiling water, stock cube and lime leaves. Turn the heat up and bring gently to the boil, then simmer for 10 minutes, until slightly reduced.
Stir in the chicken and mushrooms, reduce the heat to low and cook for a further 5 minutes, or until the chicken is cooked through, adding the mangetout, green beans or baby corn for the final 2 minutes. Taste and season. Stir through roughly chopped Thai basil leaves and coriander.Serve with steamed rice and lime wedges.