METHOD

1. Preheat the oven to 120 Celsius
2. First make the Rub. Combine all the ingredients for it in a bowl and mix well. Rub the mixture all over the brisket.
3. Place the roasting tin on the hob and add a couple tablespoons of olive oil. When hot, seal the beef on all sides until coloured. Transfer to a plate and set aside.
4. Add the onions, bay leaves, and sugar to the roasting tin along with a pinch of salt and pepper and cook over a medium heat until the onion are soft and caramelised. Add the tomato purée and stir for 1 minute. Pour over the beer to de-glaze the pan, Scraping up the bits stuck to the bottom.
5. Put the brisket back into the pan on top of the onions and pour over the beef stock. Bring to the boil, then cover tightly with foil and transfer to the oven for 6 hours.
6. Transfer to a serving dish, cover loosely with foil and set aside to rest for 15-20 minutes.
7. Meanwhile, Place the roasting tin over a medium-high heat to reduce the sauce adding the cider vinegar. Pour any of the resting meat juices into the tin as you do so.
8. To serve, slice the brisket and spoon the sauce over it.