Make fritters: 3 days ahead, cover salt cod with milk and soak, refrigerated, changing milk several times. Rinse cod under cold running water and flake.
Slowly heat oil in a deep-fryer to 360 degrees F while you prepare batter. Scrape out insides of baked potato into a mixing bowl and add salt cod, egg, parsley, onion, garlic, and baking powder. Mix it up and season with salt and pepper. Add enough flour to stiffen batter: it should be able to drop from spoon into hot grease. Test a few times before making many fritters at a time. Drop batter by spoonfuls into deep-fryer. With a long handled utensil, move them around as they fry. Drain on paper towels and serve with parsley sauce.
Make parsley sauce: In a small bowl combine all ingredients, taste and adjust seasonings.
Yield: About 15 Fritters