How to cook
Select a large bean variety. Soak them for several hours in cold water, then replace with new water and bring to the boil over a slow fire. It is important for the beans not to be over-boiled - they must be cooked but not turned into a pulp.
Allow the beans to cool in the water in which they have been boiled in. Then drain them. Cut the onion into crescents and crush it with salt. Add it to the beans, season with salt, black pepper, vinegar and olive oil.