Divide the fish into 3 roughly equal pieces, wash, pat dry and season with salt, pepper and lemon juice. Preheat the oven (top and bottom heat) to 225-250 ° C.
Grease an ovenproof dish with butter and place the pieces of fish in it. Mix the tomato paste, herbs, parmesan and breadcrumbs into the creme fraiche and season with salt and pepper to taste.
Spread the seasoned creme fraiche evenly on the fillets and cover with flakes of butter. Cook the fish in the oven for about 20 minutes.
This goes well with potatoes and rice or bread and a salad.