2tablespoonsfresh dill fronds -- chopped, or 1-2 teaspoons dried dill, added 1 teaspoon at a time, to taste
1/2teaspoonwhite pepper -- or ground black pepper
Heat a soup pot over medium heat. Brush skin-side of the salmon with melted butter and place skin-side down in the pot. Brush the salmon flesh with butter and sprinkle with blackened seasoning. (Reserve remaining butter.) Cook on each side for 3-4 minutes, then transfer to a platter and set aside. While the fish is cooking, prep bacon and vegetables.
In the same pot, cook the bacon over medium heat, stirring frequently, until browned and crisp (about 5 minutes); transfer to paper towels to drain. Continue to prep remaining vegetables while bacon cooks.
Pour off all but about 2 tablespoons fat from pan and add the onion. Cook onion over medium heat until just beginning to brown at the edges, 5-7 minutes. Add the garlic, celery, potatoes, and cook 5 minutes, stirring occasionally, until the vegetables soften. (Add a little bacon fat if pan seems too dry.)
Stir-in stock (more can be added so the vegetables are covered in stock) and salt; bring to a boil. Reduce heat and simmer, covered, until potatoes are almost tender, about 10 minutes. Add milk, bring the soup back to a simmer, cover and cook until potatoes are tender, about 8 minutes.
Break up salmon into bite-size pieces and add to the soup with any accumulated juices from the plate. Add half the bacon, dill, pepper, remaining melted butter, and simmer gently 3-4 minutes to meld flavors. Adjust dill, salt, and pepper, to taste.
Ladle into warmed bowls, garnish with remaining bacon, and serve.
Soup can be thickened by pureeing 1-2 cups of the soup in a blender then added back in, if desired. Sweet potatoes can be substituted for half the red potatoes. To thin the soup, add equal amounts of chicken stock and milk.