Peel the onions. Dice 1 onion, cut the rest into slices. Heat 1 tablespoon of oil in a casserole dish, add sauerkraut, pluck apart with a fork. Add diced onion, bay leaf and juniper berries and fry over medium heat while turning.
In the meantime clean, wash and dice the peppers and add them to the sauerkraut. Deglaze with apple juice and braise for about 10 minutes. Add apple compote and braise for another 5-8 minutes.
Season with salt and pepper. In the meantime, blanch bratwurst with boiling water. Remove, dab dry with kitchen paper and prick 2-3 times with a fork from each side. Heat remaining oil in a pan, add bratwurst and fry on medium heat for 2-3 minutes on each side.
Add the onion rings one minute before the end of the frying time. Meanwhile bring 375 ml of water and salt to the boil, remove from the heat and add milk. Add puree flakes and stir in. Stir in the fat.
Arrange sauerkraut, bratwurst and mashed potatoes sprinkled with onion rings on plates and serve as you like, garnished with marjoram and sprinkled with parsley.