Soak the liver in a little milk for 1 hour, dry with kitchen paper.
Chop the sage leaves.
Slowly fry the liver in oil, season with salt, pepper and half of the sage leaves. Add the silver onions and sauté briefly, deglaze with the stock and vinegar. Just let the liver steep.
Peel the tomatoes, cut the seeds into fillets and add to the liver, now also the rest of the sage leaves. Season to taste with salt and pepper.
Serve the liver on ribbon noodles and decorate with cress.