Peel and finely chop the onion. Peel carrots, quarter them lengthwise and cut them into slices. Wash, clean and chop the celery
Heat the oil and fry the diced vegetables for about 5 minutes, turning them over. Add meat and fry for another 10 minutes. Chop the meat with the spatula. Stir in tomato paste and fry briefly. Wash the rosemary, shake dry, pluck needles from the branches and chop. Deglaze the mincing pan with stock, bring to the boil and season with rosemary, Worcestershire sauce, salt and pepper
Peel, wash and dice the potatoes. Cook in boiling salted water for about 5 minutes. Drain the potatoes in a sieve and let them drain. First layer the mince pan, then the potatoes in an oiled casserole dish. Cook in the preheated oven (electric cooker: 200 °C/ circulating air: 175 °C/ gas: see manufacturer) for approx. 40 minutes