In a large saucepan of boiling salted water, cook potato until tender when pierced with tip of a sharp knife, about 20 minutes. Drain, peel, and mash with heavy cream, and cloves plus salt and pepper to taste. In a small skillet, melt 1 tablespoon butter over medium heat. Add onion and cook, stirring often, until softened, about 3 minutes. Stir into mashed potato. Add ground sirloin and egg yolk to potato and mix well. Stir in pickled beets and capers. Form mixture into 4 patties about 3 cm thick. Transfer patties to wax-paper-lined baking sheet, cover with plastic wrap, and refrigerate 1 hour. Dredge patties in flour; shake off excess. In a large skillet, melt remaining butter in oil over medium-high heat. Add patties and cook until bottoms are browned, about 4 minutes. Turn and cook until desired doneness, about 5 minutes for medium.