Cut the beetroot into small cubes and sprinkle with balsamic vinegar. Cut apple and gherkins into the same cubes. Dice the onion very finely. Pour everything into a bowl and add the capers (chop the larger ones first).
Separately stir the ingredients for the mustard marinade with a fork until smooth, add plenty of finely chopped herbs and season to taste.
Wash the meat, dab dry and cut into strips. Clean and wash the peppers and cut them into strips as well. Peel and chop the onion. Drain the sauerkraut. Heat lard. Fry the onions and turkey strips for 2 minutes at high heat. Season with salt and pepper. Add paprika and sauerkraut. Stir in tomato paste, fry for another 5 minutes. Season with juniper berries and laurel. Add 1/4 litre of water, bring to the boil briefly. Pour into an ovenproof dish. For the mashed potatoes bring 150 ml salted water and milk to the boil. Stir in the puree powder. Grate cheese, fold in. Spread on the sauerkraut goulash. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 15 minutes. Serve sprinkled with parsley and garnished