Leave the diced bacon in a pan, add the onions and let it become translucent.
Pour half of this mixture into a baking dish. Spread the tomatoes on top and place the fish on top. Mix the chopped herbs with the sour cream and pour over the fish - it should be completely covered. Top up with the rest of the bacon and onions and sprinkle with the breadcrumbs. Bake the whole thing in the oven at 250 ° for about 30 minutes.
Incidentally, it also tastes very good when jacket potatoes form the bottom layer.