1. In a large saucepan, cook the onion and peppers, gently in the oil for around 5 minutes, shaking or moving the pan around occasionally until soft.
2. Stir in the garlic.
3. Add the chilli and the tomato puree together and add to the pan.
4. Add half the stock and bring to the boil.
5. Cover and simmer for around 10 minutes.
6. In a food processor or blender, puree the mixture.
7. Add to the saucepan and add the rest of the stock and the lime rind and juice.
8. Bring to the boil.
9. Serve hot.