1. Slice the beef across the grain into thin strips. Combine the flour and nutmeg and use mixture to lightly dust beef strips. Brush the beef strips with the oil.
2. Preheat a large frypan to moderately-hot. Keep the heat at moderately-high. Cook the beef in 3 batches. Cook the first side until the first sign of moisture appears on the uncooked side, turn and cook other side of beef strips. Remove each batch and set it aside.
3. Add the onion to frypan and cook until soft. Add the beef stock, wine and tomato paste, stir to combine and bring to the boil. Reduce the heat to a simmer, return the beef to the pan and simmer for about 45 minutes or until beef is tender. In the last 15 minutes add the mushrooms and sour cream. Serve beef stroganoff with steamed basmati rice and steamed vegetables including green beans, carrots and cauliflower.