Using a dutch oven or a soup pot add the butter and melt it on medium-high heat.
Add the onions, cook until soft and translucent (about 5 minutes)
Add in the garlic, cooking for about 1 minute (or until fragrant).
Increase temp to bring to a boil.
Add the flour, stirring often.
Pour in the chicken broth.
Stir in the corned beef and sauerkraut.
Once it has boiled begin to reduce heat to a simmer.
Cover/ simmer for 15 minutes.
Add the sour cream, chives and 1/2 of the shredded Swiss cheese. (1/2 of the 1 cup of cheese.)
Cook for another 2-3 minutes for the cheese to melt.
Garnish with more Swiss cheese.
Serve with a rye bread.