* Use 3 3 1/4 pounds fresh skinned haddock or other white-fleshed fish with bones in it. Fry salt pork to render all fat in a heavy kettle and then remove. Add potatoes, onions, and 1/2 teaspoon salt. Cover with hot water and cook over medium heat, covered, 15 minutes, until potatoes are just tender. Do not overcook. Meanwhile, cut fish into large chunks and put into another saucepan. Add boiling water to cover and 1 1/2 teaspoons salt. Cook slowly, covered, until fish is fork tender, about 15 minutes. Remove from heat. Strain and reserve liquid. Remove any bones from fish. Add fish and strained liquid to potato-onion mixture. Pour in milk and leave on stove long enough to heat through, about 5 minutes. Mix in butter and pepper. Serve at once. Serves 4 to 6.