Clean, wash and quarter the cabbage and cut into fine strips. Peel shallots and cut 2 pieces into fine strips. Knead cabbage and shallots with salt, pepper, 1 tbsp lemon juice and 4 tbsp oil.
Peel and finely grate the horseradish. Wash apple, quarter it, remove core. Dice quarter. Mix horseradish, apple cubes and sour cream. Season to taste with salt, pepper and 1 tbsp. lemon juice
Wash the meat, dab dry and season with salt. Heat 2 tablespoons of oil in an ovenproof pan and fry the meat for approx. 5 minutes, turning it over
In the meantime, finely dice the remaining shallot for the crust. Wash the thyme and shake dry. Strip the leaves from the stalks, except for a little bit for garnishing. Chestnuts chop. Crumble the rolls into breadcrumbs. Knead butter, breadcrumbs, diced shallots, thyme and chestnuts. Season with salt and pepper. Spread the crust on the medallions. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 8-10 minutes. Arrange salad, meat and horseradish on plates and garnish with thyme