The day before, soak the beans overnight in 2 litres of cold water.
The next day peel and chop the garlic. Wash the sage, dab dry and remove the leaves. Boil the beans with sage stems and half of the garlic in plenty of water. Simmer covered for 1-1 1/2 hours until soft.
Skim off the resulting foam with a skimmer. About 15 minutes before the end of the cooking time, season the beans with salt and pepper.
Prick sausages several times. Heat oil in a casserole dish. Fry the sausages in it all around for about 5 minutes. Fry sage leaves and remaining garlic briefly. Add tomatoes and juice, chop a little and bring to the boil.
Cover and simmer for about 10 minutes.
Drain the beans and add to the tomatoes. Simmer everything for about 10 minutes. Season with salt, pepper and 1 pinch of sugar. Ciabatta tastes good with it.