Cut salt pork into tiny cubes and cook in a large pot until light golden; remove with a slotted spoon and set aside.
Discard all but about 1 tablespoon of the fat.
Add onion and cook over low to medium heat until soft.
Add potatoes and salt to the kettle.
Place fish on top of potatoes, and add enough water to cover potatoes and steam fish.
Bring to a boil and reduce heat to simmer for 10 to 15 minutes until both fish and potatoes are done. (Remove bone from fish, which can be done easily after fish has cooked.)
When fish flakes easily into large pieces and potatoes are done, add milk and correct seasonings.
Top with pork cubes.