Gather the Ingredients: Prepare and measure all ingredients before you start. This ensures a smooth and efficient cooking process.
Prepare the Roux: In a large pot over medium heat, melt the butter. Add the minced garlic and stir until fragrant. Gradually add the flour, one tablespoon at a time, stirring constantly to create a smooth mixture. Cook for 1-2 minutes until the roux turns slightly golden but not browned.
Add the broth: Slowly pour in the fish broth, stirring continuously to prevent lumps. Bring the soup to a gentle simmer.
Cook the Vegetables: Add the leek, carrots, parsnips, celery root, and potatoes to the pot. Season with salt and pepper, then stir well to coat the vegetables in the roux. Cover and let simmer for 10 minutes, stirring occasionally.
Incorporate the Cream and Egg Yolks: In a small bowl, whisk the egg yolks. Stir them into the soup, then slowly pour in the heavy cream, stirring constantly for a smooth, creamy texture. Reduce the heat to low and let the soup warm through, making sure it does not boil. Adjust with salt and pepper to taste.
Add the Seafood: Gently add the cubed salmon and let it cook for 5 minutes. Then, stir in the shrimp and cook for another 2 minutes, just until the shrimp turn pink and opaque. Season with salt and pepper if needed.
Add the Chives: Stir in the chopped chives and let the soup simmer uncovered for 10 more minutes to allow the flavors to blend.
Finish and Serve: Remove from heat and let the soup rest for 1 minute before serving. Enjoy hot with crusty bread or traditional Norwegian flatbrød.