Thick and filling Steak and Ale pie (with mash)

OK so there's a million other recipes also claiming to be the best, but here's another which is definitely the most superior ;o)

You will need:
1kg braising/chuck steak or brisket, cubed into bitesize pieces
1 large onion, finely chopped
500ml bottle of good ale (I used St Peter's Organic Bitter)
100-200ml hot water
1-2 tbsp Plain flour
1 tbsp Cornflour
2 beef stock cubes
Puff pastry (buy this as it's not worth bothering to make - unless you really want to, but you'll probably regret it)

Part One. Prepare the night before or in the morning.

1. In a wide saucepan, fry the onion til translucent, and the beef til sealed brown on the outside.
2. Add the plain flour - keep stirring so it doesn't stick - also add a little of the hot water to help but not too much.
3. Once the flour is cooked out, slowly add the beer, keeping it stirred. Slowly so it has a chance to come back to a boil, and also so it doesn't froth over.
4. Chuck in stock cubes and Bovril, and simmer til it's all dissolved nicely.
5. Add just enough more of the hot water so that the meat is only just covered.
6. If it's looking thin (it needs to be of a syrupy consistency), mix about a tablespoon of cornflour in a little cold water, and add to the pan. (If it's too thin the pastry will go soggy.)
7. Cover, and pop in the oven for 2 hours at 170C.

Part two. Pastry and serving it up.
1. Preheat your oven to 220C.
1. Put the beef and liquid into a smaller pot, so that it almost reaches the rim.
2. Line the rim with some of the pastry (makes a better seal), and then cover the pot with a sheet of pastry; trim the around the edges with a knife.
3. Cut a small hole in the middle to let the steam escape.
4. Put in the oven; after 15 mins, turn the heat down to 170C.
5. While cooking, make up some mash potato. I like to make it with lots of butter til creamy, no milk, a good dose of grated nutmeg and black pepper, with a little salt to bring out the flavours.
6. Serve, preferably with another bottle of ale. (What? You only bought one?)