Have a bass weighing about four pounds; scale thoroughly, wash and wipe dry. Cut a deep, lengthwise incision from head to tail on each side, and set on a buttered fish-sheet in a baking-pan; add a chopped onion, several branches of parsley, two cups of strained tomato and half a green pepper pod, cut in bits: season with salt and pepper and add a cup of port wine; put bits of butter on top. Heat to the boiling point, then let cook in a moderate oven forty minutes. Baste four or five times during the cooking. Thicken the liquid with butter and flour, cooked together, and strain into a bowl. Remove the skin and hard portion around the stem ends of six or eight tomatoes and season with salt and pepper: put bits of butter above each and bake till tender. Slide the fish upon a serving-dish and dispose the tomatoes on top. Surround with parsley and serve. Fine-chopped parsley and a tablespoonful of lemon juice may be added to the saucé.