Oil the bottom of a baking dish. Thinly slice one of the lemons. Put a layer of lemon slices on the bottom of the baking dish.
Put the fish on top of the lemon. Cover the fish with slices of lemon and tomato. Season and drizzle with olive oil. Bake in the oven for 20 minutes.
To make the sauce, tear up the bread and put it in a blender with the garlic and sesame seeds. Add a little water, the juice of the other lemon and a tablespoon of oil. Blend until you have a smooth thick sauce. Add more oil or seasoning if necessary.
Serve with the fish.
Nutritional information is approximate and a guideline only.