Heat the olive oil in a large, heavy-based saucepan set over a moderate heat. Sear the chicken pieces until lightly golden all over, then remove from the saucepan and add the onion and sweat for 4-5 minutes, stirring occasionally.
Add the lentils, tomato and most of the apple and stir well to combine. Add all the spices along with 1 tsp of salt. Cover with the stock, add the chicken pieces back to the saucepan and bring to the boil, cooking for 4-5 minutes.
Reduce to a simmer for 15-20 minutes until the lentils are soft and the chicken is cooked through. Stir in the coconut milk, bring back to a simmer and adjust the seasoning if necessary.
Ladle the soup and chicken into serving bowls. Sprinkle the coriander on top and serve alongside the remaining apple and the nan bread.