I put it in my oven at 200 C/400 F/Gas Mark 6 uncovered for 30 minutes and then cover with silver foil very well (completely) turn it down to 110 C/225 F/Gas Mark ¼ and leave overnight or at least 9 hours) or in the Roasting Oven of Aga for 20 mins followed by Simmer Oven overnight.
I will get it carefully out in the morning (watch out for the liquid tipping out of the tray) and pour off the liquid into a saucepan. You could put the meat back in to keep warm, or if you need the oven for Roasties etc as I do, then put to one side covered with foil and a couple of tea towels. If I am serving later on I will cover with foil, allow to cool and then refrigerate.
Wait for the juices to cool a little and take off half the fat if there is a lot of it, I save it to use for the roast potatoes.
Place the juices in a saucepan, make sure you get out all the meaty bits from the tray. add the stock and bring to a simmer. Add the water to the cornflour in a cup and stir to mix well. When the juices are simmering stir the cornflour briskly in and repeat if it is still too thin for a gravy. Season to taste. If the cornflour forms lumps in the gravy just pass it through a sieve.OR I simply thicken with Bisto gravy granules, trust me it's good as well as super quick.
Depending on how long the meat is out of the oven I will put it back in at about 180 C/350 F/Gas Mark 4 covered with silver foil to warm back up and get to temperature. Another thing I have done is to carve the meat and then put in a roasting tray and cover with the gravy. You can then reheat to temperature, ideally covered with a large piece of baking paper that has been run under the tap, scrunched up and then flattened out over the meat, followed by a top layer of silver foil. A bit of a faff but it keeps the meat so fresh, if that's the right word!
When ready simply carve and Apply to Sunday Face with all the trimmings until it hurts.
Notes
The amount of juices made do vary with each piece of brisket. I generally add 500 mls of beef stock however sometimes I only need to add 250 mls.
Another thing I have done is to carve the meat and then put in a roasting tray and cover with the gravy. You can then reheat to temperature, ideally covered with a large piece of baking paper that has been run under the tap, scrunched up and then flattened out over the meat, followed by a top layer of silver foil. A bit of a faff but it keeps the meat so fresh, if that's the right word!
I do try always to have some gravy left over to make a cottage pie with the next week. The gravy that is produced here is absolutely incredible and transforms any other beef recipe to another level.
I also try to cook more meat than I actually need as the leftover beef is very good in sandwiches or with chips for another easy meal.
Remember to make sure that your piece of meat is not the fatty end. I always ask my butcher to check.
I sometimes cook this the day before and cool before storing in the fridge until I am ready to prepare it for Sunday Lunch. I carve it cold and reheat covered in gravy in the oven or slow cooker/crock pot.