If possible do this the day before and leave in the fridge but if not then at least 30 mins before cooking.Take all the rub ingredients and mix in a bowl then simply rub all over the brisket.
Barbecue sauce and cooking
Pre-heat the oven to 160C or 140C fan/320F
In a roasting tin addd all the sauce ingredients and 2 cups water, then mix altogether and add the beef. Cover with lid or double layer of foil.
Bake for 4 - 5 hrs, then uncovered for 30 mins, until fork tender. Baste ever hour or so with pan juices. Keep an eye on the liquid so it doesn't reduce beyond a BBQ sauce consistancy. If it is, add a little water.
Once done, remove the brisket from the roasting tin so you can pour out the liquid sauce into a pan. (Then return the brisket to the roasting tray and set aside for a few minutes).For the BBQ sauce, place the pan on a hob and bring the BBQ liquid to a simmer until it thickens into a nice BBQ sauce syrupy consistency.
Now, turn the oven up to 200C/390F. Drizzle the brisket with oil and brush with the BBQ sauce (but keep back a lot of sauce for the sliders), and roast for approx 10 -15 mins to get a nice caramelisation.
Serve by thinly slicing the brisket across the grain (that's important) and serve with remaining BBQ sauce, cold slaw and some fries.