For the dressing, mix well the vinegar, mustard, salt, pepper and oil. Fold in the cranberries.
Heat the butter in a small pan. Steam the onions in it until translucent. Add the chestnuts and the stock and cover and cook for 8-10 minutes.
In the meantime, cut the bacon strips into 1 cm wide strips and slowly fry them in their own fat in a coated frying pan.
Quarter the chestnuts directly in the pan with the knife. If there is still liquid, let it boil down uncovered except for a small residue (approx. 2 tablespoon). Then add the chestnuts, onions and liquid to the prepared salad sauce.
Mix the lamb`s lettuce with the sauce and serve in deep plates. Spread the still warm strips of bacon over the top.