In a stew kettle saute chopped up onion, add potatoes, chicken broth & water; cover and cook until potatoes are tender.
In a separate pan boil sausage to get rid of the fat. Add sausage to the potatoes; add garlic powder, salt & pepper to taste. Add the saurkraut and continue to cook on low-med heat.
Make a rue; in a sauce pan melt butter, add the flour and whisk the flour in with the butter until the flour cooks fully and no longer looks white. The flour might clump up but that is ok. Add milk and whisk to incorporate until all the lumps are gone and the sauce starts to thicken. Slowly add 1/2 and 1/2 to the rue and heat it slowly - do not boil.
Add your rue with 1/2 and 1/2 mixture to the kettle and continue to cook slowly on medium heat watching and continuing to stir.