Heat the oil in a deep frying pan or wok, stir in the curry paste and fry for 30 seconds until it becomes fragrant. Stir in the chicken, then add the sweet potatoes and lentils and keep stirring to coat everything in the paste. Add 300ml water and the coconut milk. Bring to the boil, then simmer for 15-20 mins or until the chicken and sweet potato are cooked through and the consistency of the sauce is slightly thickened.

Tip in the peas, bring back to the boil and simmer for a further 2 mins, then add the tomatoes and cook for 2 mins more. Serve with steamed rice, or roti.