Heat the oil and cook the onion and garlic until soft and golden.

Add the kidney beans and water and stir in the tomato paste and spices and cook for a few minutes.

Add the lime juice to the kidney bean mixture.

Take the pan off the heat and when it has cooled a little, process the mixture until it is a bumpy puree.

When it is cool, arrange in small bowls and sprinkle over the reserved lime zest.