Peel the onion and put 4 cloves into it. Peel 2 carrots and celery and dice finely. Clean and wash the leek, cut it in half lengthwise and chop it into small pieces
Wash the meat, dab dry and rub with salt and pepper. Heat oil in a roasting pan. Brown the meat thoroughly all around, remove from the roaster. Add the vegetables, bay leaf and peppercorns and fry vigorously while turning. Add the onion and place the meat on the vegetables. Remove from the hotplate
Lightly brown 60 g butter and 70 g sugar in a pan, dust with 50 g flour and brown. Deglaze with red wine and stock, bring to the boil briefly and pour over the roast. Cover and bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 2 3/4 hours.
Wash the potatoes and cook in boiling water for about 25 minutes. Drain, quench briefly and remove the skin. Press the hot potatoes immediately through a fine potato press. Add 75 g butter, egg yolks, egg, 150 g flour, breadcrumbs and 1 teaspoon salt and knead to a smooth dough (mixture sticks a little)
Place the potato dough on a piece of foil, spread it evenly with floured hands to form a rectangle (28 x 33 cm) or press it. Roll up from the long side and wrap tightly in a clean tea towel (remove foil). Tie ends together with kitchen thread
Heat plenty of salt water in an elongated roaster. Cover the potato roulade in a tea towel and let it simmer for about 45 minutes
Meanwhile peel, wash and slice 3 carrots. Clean, wash and slice the fennel. Drain black salsifies and cut into pieces. Wash the rosemary, shake dry and, except for a few needles for garnishing, pluck the needles from the stalks and chop roughly.
Heat 50 g butter in a saucepan, add carrots, fennel and rosemary, cover and steam for about 15 minutes. Stir several times. Add the black salsifies 3 minutes before the end of the cooking time. Season with coarse salt and chilli flakes, keep warm
Remove the roaster from the oven. Remove meat from the sauce, keep warm. Season sauce again with salt, pepper and 1 pinch of sugar. Wash parsley, shake dry and chop finely. Lift the potato roll out of the water, let it drip off a little, cut into slices
Arrange meat with sauce and vegetables on a plate. Garnish with rosemary. Add remaining sauce and vegetables. Sprinkle potato slices with parsley