Put boiled beef in boiling water with peppercorns, cloves, juniper berries, bay leaves, onions and tomatoes. Cook for 2.5 hours.
Let the meat cool down completely. Then cut into very thin slices. Line a plate with it.
Cut the spring onions into thin rings. Spread on the meat. Prepare a marinade with vinegar, oil, pepper and salt.
Heat the butter in a pan, toast the bread cubes in it until light brown. Pour the marinade over the meat with the spring onions and spread the bread cubes over it. Serve immediately.