Put the fish in a pot, cover it with water, bring to a boil, reduce the heat, and simmer until the fish is tender. (The time will depend on how hard it was cured and how long it was smoked.) While simmering the fish, sauté the salt pork in a skillet until the pieces begin to brown. (Some cooks may want to put the salt pork in with the fish instead of browning it; suit yourself.) Drain the salt pork and sauté the onion in the skillet for 5 minutes.
When the fish is tender, remove it from the pot, and flake the meat, discarding the bones. Add the potatoes, salt pork, and pepper to the pot. Cover and simmer for 10 minutes. Then add the onion and simmer for another 10 minutes or so, or until the potatoes are done. Stir in the fish flakes. Slowly add from 2 to 3 cups of milk, stirring and tasting as you go. Ladle the chowder into bowls and serve with plenty of hot bread. A loaf of chewy-crusted French or Italian bread suits me better, but hot biscuits or even bannock will do. I like to grind some more black pepper onto my serving.