Wash beans in cold water:

Then put the beans into a pan of cold water and leave it for overnight soaking, preferably in soft water:

After soaking in cold water, they should be boiled fast for 10 minutes before they are simmered on top of the stove or in an electric, slow cooker. This is particularly important, to destroy a poisonous enzyme present in the bean. Cooking time: after soaking, 1-1 1/4 hours: