Wash the beans and cut into bite-sized pieces. Peel the potatoes and cut into small cubes. Cut the onion and garlic into small cubes.
Heat the oil in a saucepan and lightly fry the onion and garlic in it. The onions should only be translucent, not toasted. Add the beans and potatoes and sauté for a few minutes. Pour in the stock and let the beans and potatoes steep in it. Add the strained tomatoes and bring to the boil again. Let reduce a little without the lid. Season to taste with the spices.
A dash of cream goes very well with the ready-to-serve soup.
Of course, the recipe can also be made with fresh tomatoes. Simply add these with the beans and potatoes and let them soften.