Heat some oil in a sauté pan on stove at a high heat. When the pan is smoking, add the meat and brown on all sides.
The sauté pan should have a lot of residue in it. Don't waste that flavour, keep the pan on the heat and pour half a can of Guinness in it, then with a wooden/plastic spatula scrape the bits from the bottom and transfer that and your meat to the pan in which you are going to stew in.
Add a little more oil to the pan and sweat off the onions until soft. Add to stew pan.
In that stew pan you should now have your meat, onions, and the Guinness you used to de glaze the pan with. Bring it to the boil. When boiling add the MAGGI Rich & Rustic Tomato Sauce and the beef stock then simmer.
This will now have to simmer from anything up to two-three hours, all the time checking on taste, if it needs more liquid etc.
Sweat off the mushrooms and add to stew. The cook time is only a rough guide. Cook until meat is tender.
Put into pie dish cover with pastry, glaze with egg and bake until golden brown.