1. Salt the fish steaks on both sides; dip in flour and shake off the excess. In a heavy 12-inch skillet, melt 2 tablespoons of the butter and 1 tablespoon of the oil.
2. When the foam subsides, add the fish and cook for 2 ½ minutes on each side, or until lightly browned. Remove to a platter.
3. Heat the rest of the oil and butter in the skillet, and when the foam subsides, add the onions. Cook them for 3 to 4 minutes, or until they are translucent.
4. Add the tomatoes, wine, vinegar, tabasco peppers and white pepper. Bring to a boil and stir. Return the fish to the skillet and simmer, tightly covered, for 10 to 15 minutes.
5. Arrange the fish steaks on a platter and pour the sauce over them and serve.
