Lightly salt the fish fillet (cod, redfish, salmon) and top with smoked salmon.
Dice the onion, sauté and deglaze with wine and fish stock. Place the fish fillets on top and cook over low heat, about 10 minutes. Take out the fillets and keep them warm.
Let the sauce reduce a little with the light sauce thickener and cream. Skin the tomatoes, dice the seeds and add. Add fresh basil and cooked diced potatoes and let them steep. Place the fish fillets on top and serve.