Pour 200g of the yoghurt into a bowl. Add the tandoori spice mix and mix well. Add the chicken and marinade in the fridge for 3 hours.

Place the Sweet Potato in a microwavable bowl and cover with a damp kitchen towel. Microwave on high for 2 minutes.

Fry the onions, pepper, sweet potato, ginger, garlic and chilli until the onion turns clear. Remove vegetables and set aside.

Fry the chicken until sealed then return the vegetables. Add the Tomato Puree, water and remaining spices. Stir well and simmer until reduced.

10 minutes before serving, add the remaining yoghurt and stir well.