thumb-sized piece ginger, peeled and thickly sliced
400g can coconut milk
small bunch coriander, roughly chopped
150ml pot natural yogurt
1 tbsp tomato purée
juice 1 lemon
1 tsp each hot chilli powder, turmeric, ground coriander, ground cumin, garam masala and ground cinnamon
6 garlic cloves, whizzed to a paste with the ginger
½ finger-length piece ginger, whizzed to a paste with the garlic
few drops red food colouring (optional)
Mix the marinade ingredients with 2 tsp salt and 1 tsp black pepper. Slash the legs of the chicken a few times, then rub the marinade all over, including under the skin of the breast. Marinate in the fridge for up to 24 hrs.
Heat oven to 200C/180C fan/gas 6. Put the onions, lemon halves and ginger in a roasting tin. Sit the chicken on top and roast for 1½ hrs or until the thigh juices run clear when tested with a skewer.
When the chicken is done, lift out of the tin, sit in a new dish, cover loosely with foil and leave to rest. Fish out the ginger from the tin and discard. Scrape out the roasted middles from the lemons into a food processor, add the onions and any pan juices, and whizz to a purée. Scrape the purée back into the tin and sit on the hob. Stir in the coconut milk and bubble gently, scraping up any chicken bits that have stuck. You can add a splash of water if the sauce is too thick. Stir in the coriander and serve with the chicken.