1 Tbs mustard
1 tsp sugar
Salt, black pepper
1 lb (500 g) mushrooms
1 lb (500 g) onions
2 lb (1 kg) fillet of beef
2 cartons of sour cream
- Mix the mustard with the sugar, one pinch of salt and one tablespoon of hot water into a thick paste and leave to simmer.
- Wash the mushrooms and slice.
- Peel and chop the onions.
- Brown the mushrooms and onions in oil, cover and cook gently for 20 minutes, stirring occasionally.
- Pour away the liquid.
- Cut the fillet across the grain into thin slices, dividing these into strips.
- In another skillet heat the oil on a high temperature and sear the strips of meat in batches.
- Turn and brown on all sides, using a slotted spoon to transfer the meat to the mushrooms in the other skillet.
- Season with salt and pepper, mix in the mustard paste and stir in the sour cream.
- Cover and heat, stir and serve.