1. Add to the reserved clam juice with fish stock or vegetable stock to make 2-½ cups.
2. Cut clams in bite size pieces. Set aside.
3. Add the salt pork to a small skillet and melt over medium heat. Strain, return 2 tablespoons fat to a stockpot, reserve scraps that are trapped in strainer.
4. Heat fat over low heat. Add finely chopped onion and sauté until golden.
5. Sprinkle flour over sautéed onion. Sauté 3 minutes.
6. Stir in diced potatoes and clam juice.
7. Cover stockpot with lid. Simmer 10 minutes.
8. Stir in clams. Simmer 10 more minutes, or until potatoes are tender.
9. Stir in milk, Butter, salt and pepper. Simmer until butter melts. Stir to incorporate.
10. Place pork scraps in individual soup bowls.
11. Hollow out bread loaf. Ladle hot chowder into center of bread. Serve hot.