For the beans with bacon, chop the onion and fry well at the same time with the diced bacon. If the bacon is very lean, add a little oil.
Finally, fry the tomato paste a bit as well. When the bacon is nice and glazed, add the beans with the juice from the can and, if necessary, add some water (or vegetable soup).
Season with salt, pepper and marjoram and simmer for about 10 minutes.