Soak the beans in water the night before.
Boil the beans until almost perfectly soft with a little salt in the water.
Chop half an onion and sauté it in 1dl of oil until yellow.
Add 2 big spoons of tomato puré and let it sit for about 30 seconds.
Pour in 7 dl of water, 1 full teaspoon of salt, and the beans.
Cover and let it cook on medium heat for about 15 minutes.
Check the salt and adjust if necessary.
