Clean and wash the celery and cut it into fine strips. Scald tomatoes with boiling water, peel, quarter, seed and cut into narrow strips. Put celery in a pot and add approx. 1/8 litre salt water and fat, bring to the boil, cover and stew for 15-20 minutes at medium heat.
Add the tomatoes to the celery, fold in and heat briefly. Remove vegetables with a skimmer and keep warm. Wash the sole fillets and sprinkle with lemon juice. Wash and finely chop the parsley.
Peel and halve the onion. Sprinkle fish with salt and parsley, roll up and pin with wooden sticks. Add white wine, peppercorns, bay leaf and onion to the vegetable stock and bring to the boil.
Add the sole rolls and let them simmer at low heat for about 10 minutes. Remove fish from the stock, remove wooden sticks, arrange sole rolls on a plate, keep warm. Sieve the brew.
Add the sauce thickener while stirring and bring to the boil once. Refine with crème fraîche and season to taste with salt. Pour the sauce over the sole rolls and serve with the vegetables. Buttered potatoes taste good with it.