Add the diced salt pork to a large stock pot, place over medium heat, and cook slowly till browned.
Remove the salt pork with a slotted spoon, and set aside.
Add the butter, fresh cracked black pepper, and diced onions. Cook until onions are translucent.
When onions are tender, add in the potatoes and the fish broth. Bring to a boil.
Just as the broth begins to boil, place the thicker pieces of the cusk in the middle of the pan, then cover and allow to cook for 5 minutes.
Add the thinner pieces of cusk around the edge of the pan, cover and continue to cook about another 5 to 6 minutes.
At this point the potatoes should be tender and the fish should be cooked. Break the fish into pieces with a fork.
Reduce the heat to low, add in the corn and the milks. You may need to re-season at this point, and salt can be added if needed. Gently stir the chowder to mix all the ingredients.
Shut the heat off and mix in the cooked salt pork, allow to cool, and refrigerate.
Make this in the morning to serve that night. Slowly reheat, and serve with your favorite chowder crackers.