Cut pumpkin into quarters, remove seeds, peel (do not peel Hokkaido) and dice coarsely. Peel, wash and roughly dice the potatoes. Cover the potatoes and pumpkin and cook in salted water for about 20 minutes.
Peel and finely chop the onion. Knead minced meat, 1 tbsp. yoghurt, mustard, tomato paste, breadcrumbs and onion. Season with salt and pepper.
Make meatballs from it. Heat the oil in a pan. Fry the meatballs for 8-10 minutes.
Drain the potatoes and pumpkin. Add milk and mash everything with the potato masher. Season to taste with salt and nutmeg.
Wash the herbs, shake dry and chop or cut into small rolls. Mix the remaining yoghurt and herbs. Season to taste with salt and pepper. Serve everything.