Slovak Christmas Eve Mushroom Soup - cooking recipe

Ingredients

1 -2 lb onion, chopped
1 1/4 cups butter, divided (May need a little more)
2 lbs mushrooms, finely chopped (we use white mushrooms)
1 quart water
10 (7 1/2 ounce) cans sauerkraut juice
1/4 cup flour

Preparation

Saute chopped onions in 1 cup butter until golden brown.
Add finely chopped mushrooms to onions, and cook until mushrooms are done.
Add water and cans of sauerkraut juice, bring to boil, lower heat and simmer 1/2 hour.
In a small sauce pan brown remaining 1/4 cup butter, adding flour to make a roux.
Slowly add some soup juice (about 2 cups) to the roux, stirring to blend.
Add roux to soup and cook another 15 minutes to 30 minutes. Serve.