Prepare the stangesellerie (ready to cook, e.g. peel, remove woody parts and dirt), cut large branches in half lengthwise, then cut the vegetables into stalks about three cm long. Peel the carrots and cut them into wheels. Remove the skin from the onion and chop finely.
In a medium frying pan, melt the butter. Sauté the onion in it. Add the celery and carrots and sauté. Extinguish with white wine or soup and reduce by half. Then stir the crème fraîche until smooth, add and season everything together with salt and pepper. Meanwhile, let the vegetables soften for twenty minutes with the lid closed.
Finely chop the dill and add to the vegetables, seasoning if necessary.