Dab meat dry and rub with salt and pepper. Heat clarified butter in a roaster. Fry the meat in the pan for about 10 minutes. Cook in the preheated oven (electric cooker: 80 C/circulating air and gas not suitable) for 2 1/2-3 hours.
Wash the herbs and shake dry. Chop chives and dill finely. Chop parsley finely. Peel and chop onion. Mix quark and crème fraîche. Stir in onion and herbs. Season to taste with salt and pepper.
Peel the garlic and cut into thin slices. Peel and wash the potatoes and cut them into halves or quarters depending on their size. Cover with garlic and cook in salted water for about 20 minutes.
Wash the pumpkin, quarter lengthwise and remove the seeds with a spoon. Wash the rosemary, dab dry and remove the needles.
Drain the potatoes. Add 2 tablespoons of butter and melt. Cover the potatoes and shake them vigorously in the pot and place them on a baking tray with the pumpkin. Add 2 tablespoons of butter in flakes.
Remove the roast beef from the oven, wrap in aluminium foil and leave to rest. Turn up the oven (electric cooker: 225 °C/circulating air: 200 °C/gas: level 4).
Baking tray with potatoes and pumpkin in the oven 30-35 minutes. After about 15 minutes turn the pumpkin and potatoes. Spread rosemary on top.
Cut the lukewarm roast beef. Serve with potatoes and pumpkin, sprinkle with sea salt. Add the herb quark.