Bring the stock to the boil, add the chicken breasts, cover and simmer on a low heat for approx. 10 mins. Remove, cover and set aside. Pour the stock into a measuring jug.
Heat the oil in the same pan. Sauté the sweet potato and parsnip. Add the curry and lemongrass, cook for about another 3 mins. Pour in the stock and coconut milk, bring to the boil, reduce the heat, simmer for approx. 25 mins. Blend the soup, season with salt.
Slice the chicken breasts into thin strips, add to the soup with lime juice. Reheat the soup, serve in pre-warmed dishes. Place the apple, mango and chilli on top.