1. In a deep pan, saute the chopped onion in a little olive oil. Add the cumin, garlic and the paprika, sauteing for 1-2 minutes. Add the tomatoes in with the juice, water, salt, pepper, tomato paste and the two cilantro bunches.
2. Bring the mixture to the boil and then lower the heat. Cover and simmer for 30 minutes. While the soup is cooking, the remaining cilantro leaves should be washed and dried. Reserve a little (about 1 cup) for garnishing.
3. After 30 minutes, remove the bundles of cilantro leaves from the soup. Pick any out that have broken off. Puree the soup in a food processor and then, food mill or an immersion blender.
4. Turn the heat back onto the soup and then add the lime juice, cayenne pepper and the chopped cilantro. Cook for about 2-3 minutes. Serve the soup hot with the chopped cilantro sprinkled on top as a garnish.