Melt butter in a large Dutch oven over medium high heat. Add onions and saute until golden, about 7 minutes. Remove to a large bowl.
Brown meat in Dutch oven and three batches, allowing about 10 minutes per batch and removing to bowl as it browns.
Blend the paprika with the warm water and the salt and pepper.
Return onion and meats to pot along with any accumulated juices, the paprika mixture, and beef broth, and bring to a boil. Adjust heat and simmer mixture until all meats are tender, about 2 hours. Check pot occasionally and add a little more water if mixture threatens to scorch.
Mix in sauerkraut, cover and simmer 10 minutes, then smooth in sour cream and heat through 5 minutes. Do not allow to boil or sour cream will curdle. Taste for salt and pepper and add if needed.