Place a medium saucepan, lightly coated with olive oil, over medium heat. Sweat the onion and garlic until they are very soft and fragrant (about 10 minutes).
Add the remaining ingredients and simmer for about 40 minutes until the mixture is very thick. To test the doneness of the ketchup: spoon a small amount on to a plate and place the plate in the refrigerator for 10 minutes. Check the consistency of the ketchup to see if it is thick and holds together. If it is thin and watery, continue cooking for another 10 minutes and test again.
Puree the ketchup in a blender or with an immersion blender. Adjust seasoning with salt and pepper. Store the ketchup covered in the refrigerator for up to 1 month or freeze up to 3 months. If you want to can the ketchup-follow canning directions.
*Pimenton is Spanish smoked paprika. Peppers are smoked over oak and then processed into paprika. Pimenton adds complexity and a slight sweetness to ketchup. Pimenton can be found in most grocery stores or online.