Heat the oven to 200°C/400°F, place a pan of water in the bottom of the oven. Peel the leave away from the cauliflower then turn upside down and cut away the bottom of the stalk making sure to keep the head of cauliflower in tact. Place on a baking sheet or in an oven proof skillet.
Mix together all the ingredients for the tandoori paste and season to taste. Turn the cauliflower upside down and pour 3/4 of the paste over the bottom of the cauliflower and allow it to run throughout all the cauliflower stalks. Turn the cauliflower the right way up and brush on the rest of the paste as well as any that ran off into the pan.
Put the cauliflower in the oven and cook for 50 minutes to an hour until tender. While that's cooking mix together the ingredients for the sauce. Serve with naan and rice if desired.
Nutrition information is an estimate and will vary depending on the exact ingredients used.