- 2 lb beef fillets, fat removed
- 1 tablespoon of mustard powder
- 1 tablespoon of sugar
- 4-5 tablespoons of vegetable oil
- 4 cups of onions, thinly sliced
- 1 lb of mushrooms, thinly sliced
- 2 teaspoons of salt
- 1 teaspoon of fresh ground black pepper
- 1 pint of sour cream
Combine the mustard, sugar, a pinch of salt and a small amount of hot water into a mixing bowl to form a thick paste consistency. Set aside to allow the mustard paste to cool down for about 15 minutes.
Heat 2 tablespoons of oil in a 12 inch saucepan over a high heat. When hot place in the mushrooms and onions. Cover the pan, reduce heat and allow to simmer for about 20-30 minutes, stirring occasionally, until all the vegetables are well cooked and soft.
Drain the cooked vegetables with a sieve. Remove excess liquid from the cooking process and return the vegetable mixture back into the saucepan.
Using a sharp knife cut the beef fillet into 1/4 inch bite size pieces.
Heat some more vegetable oil in a different 12 inch saucepan over a high heat.
Stir in half of the meat, tossing constantly with a large spoon for 2 minutes, until lightly browned. Transfer the cooked beef to the same saucepan as the vegetables, and cook the remaining meat, adding more oil if required.
When all the beef has been cooked and added with the vegetables, stir in the remaining mustard paste, salt and pepper.
Gradually pour in the sour cream, one tablespoon at a time. Add the remaining sugar and reduce to a low heat.
Allow to simmer for an additional 2-3 minutes, until the sauce is cooked and taste for additional seasoning.