Pre heat oven to 165˚C/Fan 145˚C/Gas 3. For the BBQ sauce: Add all ingredients into a pan, mix well and slowly bring to the boil. Allow to simmer for 5 minutes then set aside to cool.
For the pickled chilies and cucumber: Mix all ingredients in a pan over a low heat until the sugar is melted. Allow to cool before pouring over the chilies and cucumber. Leave to sit in the liquid for a minimum of one hour.
For the Brisket: mix all the dry rub ingredients together and rub into the beef, wrap well in 5 layers of tin foil and allow to sit in the fridge overnight.
Place the brisket in the preheated oven and cook for 4-5 hours at 160˚C or until the core temperature reaches 160-170˚C.
Once cooked remove from the oven and allow to cool completely before unwrapping. Serve on soft buns with the barbecue sauce and pickles.