Cook the sausage with celery, carrots and wine at 150 °C for about 1 ½ hours in a roasting tube in the oven. Cool for one night in the foil in the broth.
One day later, degrease the broth and pour it through a sieve. Season to taste. If too salty, carefully bring to “eating quality” with a little bit of boiling hot water.
Add the white wine vinegar, grape seed oil and sunflower oil or other vegetable oil to the stock and whisk to combine. Stir the cornstarch with a little cold water until smooth and whisk into the simmering gravy, whisking well.
Remove from heat, season heartily with pepper and add cumin liqueur by the teaspoonful. The flavor should be sweet-sour-spicy. Cool.
Cut the cooked Kassler into narrow slices. Pull each slice through the stock on both sides. Spread a small amount of stock evenly on a deep wide platter, lay the slices on top like a roof tile.
Finally, carefully spoon stock over the top. Sprinkle with coarsely chopped flat-leaf parsley and leave to infuse overnight. Serve at room temperature. Serve with a white cabbage salad or possibly a moderate sauerkraut salad (=> separate recipe) and a hearty farmer’s bread or possibly also a potato salad.