Cut the fish into slices, put in a baking dish and season to taste.
Cut tomatoes in half, if you have ordinary tomatoes, then cut into cubes. Add to the fish.
Mix sour cream with mustard.
Grate cheese on a coarse grater and add to sour cream.
Distribute sour cream over fish with tomatoes. Bake at 180 degrees 30 minutes.
Baked cod with cheese and tomatoes is ready to serve, sprinkled with herbs.