For the fish goulash, dice the fish (4 cm), coat in flour and fry in 40 g of butter. Peel and finely chop the onion and fry in the rest of the butter.
Dust with paprika powder, deglaze with lemon juice and stir in tomato paste. Pour in about 70 ml of water, stir in fish cubes and finish stewing the fish goulash for 10 minutes.