Work the minced meat, breadcrumbs, onion, eggs, salt and pepper into a smooth dough. Shape 12-14 meatballs out of this.
Leave out the herb butter, sauté the onion, add the cucumber slices and sauté briefly. Deglaze with vinegar. Take the cucumber out of the pot with the slotted spoon.
Pour in the cream and vegetable stock, season, add meatballs and cook gently for 10 minutes. Add the cucumbers again and simmer gently for another 10-15 minutes, thicken with cornstarch, season to taste and fold in the dill.