Cut the fish fillet into small cubes and season. Peel and finely chop the onion and clove of garlic.
Heat the oil in a tall saucepan and fry both until golden. Add tomato paste and sauerkraut and season with salt, pepper and chili powder. Deglaze with the vegetable stock / fish stock.
Clean the pepper and cut into fine strips. Place the fish and peppers on the sauerkraut and cook them all together for another 20 minutes.