Mix the tomato sauce and molasses (honey or brown sugar). Cut the onion into chunks, wash the tomato.
Lubricate the fish with the mixture, set aside for 15-30 minutes.
Turn it over a couple of times.
Preheat the pan, brush the fish with vegetable oil. Put the fish on parchment, skin down, add salt and fry for 3 minutes, the heat is above average. Also fry the onion and tomato slices.
Carefully turn over, remove the parchment, add salt and fry for another 2-3 minutes, the heat is above average.
Place on a platter, serving with grilled vegetables and herbs.