1. Heat the oil in a pan and cook the beef in small batches to brown. Transfer to a casserole dish.
2. Add the onions and garlic to the pan and fry until lightly browned.
3. Return the meat to the pan and stir well
4. Pour the water over the Major Roast Beef Stock Base Paste and mix well.
5. Add the stock, ale, sugar, vinegar, bouquet garni, mustard and mushrooms and season with pepper.
6. Bring to the boil. Return to the casserole dish and cover.
7. Cook in a pre-heated oven at 160°C for 3 hours or until the meat is tender.
8. Stir in the corn flour and remove bouquet garni.
9. Chill and use as required for pies.