Combine 2 tbsp of the spicy tomato sauce and natural yogurt and mix well
Spatchcock your chicken by removing the back bone. You do this by placing the chicken breast side down with the legs facing you. Cut along each side of the bone to remove it, pressing down hard on your knife to break through the ribs. Press down on both wings at the same time until you hear the breast bone crack. Cut off the wing tips at this time.
Rub 1/2 the marinade under the skin and leave to rest for 2 hours. If you don't have time to leave you can cook immediately but it is better if you can let it rest.
Preheat the oven 180 C or 350 F or Gas Mark 4
Place the chicken on a roasting tray and add some water. The water will mix wit the juices and will be used to make the gravy later. make sure to top up the water if it starts to dry out.
Cook in the oven for about 45 minutes until fully cooked. Use a meat thermometer to verify that it is full cookedLeave to rest for 10-15 minutes making sure to cover with tin foil and a towel to keep it hot
Add the remaining marinade, 1 tbsp spicy tomato sauce and 1 tbsp cornflour to the roasting juices and heat on a ring. Mix well to ensure no lumps until it comes to the boil. If the sauce is too thick you can add some water and if it needs thickening add more cornflour.
Serve with roast potatoes and steamed green vegetables