Rinse and drain the beans. Wash, clean, quarter and seed the tomatoes. Cut the flesh into small cubes. Peel garlic, press through a garlic press. Wash sage, shake dry and pluck leaves from the stalks.
Roughly chop 4 leaves. Fry garlic and chopped sage in hot oil. Deglaze with white wine and reduce by half. Stir in 100 ml water and stock. Add beans and tomatoes, simmer everything for 7-8 minutes, stirring several times.
Season to taste with salt and pepper. Meanwhile rinse liver and pat dry. Season with salt and pepper, dust lightly with flour. Heat 2 tablespoons of oil in a pan. Sauté sage leaves briefly in it, remove.
Fry liver in hot oil, turning, for 3-4 minutes, keep warm. Deglaze the gravy with vinegar and 32 tablespoons of water, bring to the boil briefly. Season with salt, pepper and 1 pinch of sugar. Serve in portions with liver, beans and roasted sage.