Heat the olive oil in a large pan. Fry the bacon and onions in the pan over a moderate heat until coloured.
Roughly chop the tomatoes and add them to the pan when the bacon is starting to crisp and the onion is translucent.
Add the smoked paprika and star anise, and season well with salt and freshly ground black pepper.
Pour in 1 litre/1¾ pints of water and cook over a moderate heat with the lid on for 30 minutes. Stir every 10 minutes.
When 30 minutes have elapsed, tip in the drained pinto beans and cook for a further five minutes.
If you intend to freeze the soup, allow it to cool to room temperature and then fill six freezer bags. Freeze for up to a month.
When you wish to cook the soup, de-frost thoroughly and, when reheating, ensure that that you bring the soup to a vigorous boil.