Blend together tomato puree, yoghurt, garam masala, chilli powder, garlic, mango chutney, salt and sugar together to form a paste.
Heat oil in a wok until it starts smoking. Add the yoghurt mix. When the sauce is boiling, add the chicken cubes and stir until coated in the sauce. Add the water and bring to a boil. Add chilli, if using, and cream. Simmer 10 minutes or until chicken is cooked.
Sprinkle the coriander on top and serve with basmati rice and naan bread.