To make the paste. Reconstitute the chipotles by soaking in boiled water until soft.Dry fry the tomatoes until blistered, remove from pan and set aside. Clean the pan, add veg oil, slowly cook onion, until soft, add garlic for a few mins, add vinegar. Peel skins off tomatoes, and blend all ingredients including lime until smooth. Can be made early and placed in fridge.