For the marinade, combine all the ingredients and mix through the chicken in an oven proof dish (in a single layer). Season with salt and pepper. Marinate for at least 3 hours or preferably overnight.
Preheat the oven to 200 °C. Bake the chicken, covered, for 1 hour.
For the sauce, heat a splash of oil and the butter in a large oven proof frying pan. Fry the ginger, garlic, curry powder, cumin and paprika for 1 minute until fragrant.
Add the tomato paste, tomatoes and sugar and cook for 5 minutes. Stir through the cream. Season with salt and pepper.
Remove the chicken from the oven and add directly to the hot sauce (discard marinade). Cover and bake for 1 hour or until tender.
For the avo crema, blitz together the yoghurt and avocado until smooth. Season with salt and pepper.
To serve, combine the avocado with a squeeze of extra lemon juice and coriander. Season with salt and pepper. Serve with the curry, rice and avo crema.