In a large pot, melt the butter over medium heat. Add the chopped onion and celery, and sauté until softened, about 5 minutes. Stir in the minced garlic and cook for an additional minute.

Add Potatoes and Stock

Add the diced potatoes to the pot and pour in the fish stock. Bring the mixture to a boil, then reduce the heat and simmer until the potatoes are tender, about 15 minutes.

Incorporate the Seafood

Once the potatoes are tender, gently stir in the smoked salmon and smoked haddock. Simmer for another 5 minutes until the seafood is heated through.

Finish with Cream and Sherry

Stir in the heavy cream, sherry, salt, and black pepper. Allow the chowder to heat through without boiling, and adjust seasoning if needed.

Garnish and Serve

Remove from heat and stir in the fresh dill. Serve hot, garnished with additional dill if desired.