Peel, wash and chop the potatoes and celery. Cook in boiling salted water for about 20 minutes. Wash the fillets, dab dry. Wrap 1 slice of bacon around each fillet.
Heat the oil in a pan and fry the fillets all around. Fry over a low to medium heat for 8-10 minutes, turning over. Wash the rosemary, dab dry and chop coarsely. Drain the cranberries, collecting the juice.
Remove the hare fillets from the pan, season with salt and pepper and keep warm. Roast the rosemary briefly in hot frying fat. Deglaze with stock and approx. 50 ml collected cranberry juice. Let it boil down a little over high heat.
Drain the potato-celery mixture and let it steam off briefly. Heat the milk and fat, finely mash the potato mixture and add the milk and fat mixture. Season to taste with salt and nutmeg. Add cranberries to the sauce, season with salt and pepper.
Serve the hare fillets with jus and puree. Salad tastes good with it.