For the boiled beef in Riesling jelly, cut the boiled beef into small cubes.
Mix vinegar, oil, salt, pepper and mustard to a marinade and let the meat marinate in it for at least one hour.
In the meantime, bring the wine and soup to the boil for the jelly. Squeeze out the soaked gelatine, dissolve in it and let everything cool down again.
Now pour a little liquid jelly into a suitable tureen mold and let it slightly stick in a cold place.
First sprinkle in finely chopped chives, then add meat cubes, onions and capers.
Pour the remaining jelly and let it set in the refrigerator overnight (but at least 6 hours).
Before turning out, place the mold briefly in hot water. Cut the jelly into thumb-thick slices and serve.