1½  pounds (600 gm) lean sirloin beef steak
6 - 8 white button mushrooms, sliced
3 medium onions chopped
2 cloves garlic, minced
2 cups (500 ml) beef stock
5½ ounce (156 ml) can of tomato paste
1½ cups (375 ml) sour cream
2 tbsp (30 ml) flour
3 tbsp (45 ml) olive oil
salt & pepper to taste
Hot cooked fettuccine noodles

Trim excess fat from the beef and cut into 1/2" x 2" ( 1 cm x 5 cm) strips across the grain of the meat. Season with salt and pepper.
Heat a large frying pan until very hot, add the oil and cook the beef strips quickly - cooking in about three batches so that it fries and doesn't start to stew. Add the onion and continue to cook a few minutes more, then add the garlic and mushrooms.
Add the tomato paste and the beef stock, mix well, bring to a boil and continue to simmer.
Combine the flour and the sour cream in a small bowl then carefully add this to the pan, stirring well. Do not allow to boil but maintain the temperature until pasta and side dishes are ready.