Ingredients

• 2 tablespoons butter
• 2 cups chopped onion
• 2 stalks celery, chopped
• 5 cups chicken stock, divided
• 5 cups diced potatoes
• 2 pounds cod, cut into 1/2-inch cubes
• 1/2 teaspoon parsley, or to taste
• 1/8 teaspoon seafood seasoning (such as Old Bay®), or to taste
• 1 pinch garlic salt, or to taste
• salt and ground black pepper to taste
• 1 tablespoon all-purpose flour
• 1 (8 ounce) bottle clam juice
• 1 tablespoon cornstarch
• 1/3 cup cold water
• 2 cups half-and-half

Instructions

1. Melt butter in a large stockpot over medium heat. Cook and stir onion and celery in hot butter until tender, about 5 minutes.
2. Pour 4 cups chicken stock into the pot; add potatoes. Bring the liquid to a simmer, reduce heat to medium-low, and cook until the potatoes are beginning to soften, about 10 minutes.
3. Stir cod into the stock with the remaining chicken stock; season with parsley, seafood seasoning, garlic salt, salt, and black pepper. Stir flour into clam juice with a whisk until smooth; add to soup. Cook and stir until the liquid begins to thicken, 5 to 10 minutes.
4. Beat cornstarch into cold water with a whisk until smooth; stir into soup. Cook just long enough for the cornstarch slurry to get warm and begin to thicken the liquid even further, about 5 minutes.
5. Remove pot from heat. Stream half-and-half into the soup while stirring.