Instructions
1. Sauté the Aromatics
In a large Dutch oven or heavy-bottomed pot, heat the olive oil or butter over medium heat. Add the chopped onion and celery and cook, stirring occasionally, until softened, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant.
2. Make the Roux
Sprinkle the flour over the cooked vegetables. Stir constantly and cook for 1-2 minutes to get rid of the raw flour taste. The mixture will be thick and pasty.
3. Build the Broth
Gradually whisk in the beef broth, making sure to scrape up any browned bits from the bottom of the pot. Whisk until the flour is fully dissolved and the mixture is smooth. Bring to a gentle simmer and cook for 5 minutes, until it begins to thicken slightly.
4. Add Dairy and Corned Beef
Reduce the heat to low and stir in the milk and heavy cream. Add the chopped corned beef and the rinsed, chopped sauerkraut. Let the soup simmer gently for 10-15 minutes to allow the flavors to meld. Do not let it boil, as this can cause the dairy to curdle.
5. Melt in the Cheese
Remove the pot from the heat. Gradually stir in the shredded Swiss cheese, a handful at a time, until it is completely melted and the soup is smooth and creamy.
6. Finish and Serve
Stir in ½ cup of Thousand Island dressing. Taste the soup and season with salt and pepper as needed (remembering that the corned beef and cheese are already quite salty).
Ladle the soup into bowls. Garnish with a drizzle of extra dressing and a sprinkle of fresh parsley or chives. Serve immediately with slices of rye toast, rye croutons, or a classic Reuben sandwich on the side.
