Heat the oil in a pan and dust the beef with flour, shaking off any excess. When the oil is hot, add the meat and onion. Brown the meat, then add pickle, mushrooms, and paprika. Add the red wine, then the stock. Bring to a boil and reduce heat to simmer for 10 minutes. Add sour cream, heat through, correct seasoning with salt and pepper, and serve with Spaetzle.