This sauce is great on burgers, chicken wings, pork ribs, brisket etc. 

Ingredients
500ml bottle of Guinness  
100g brown sugar 
100g ketchup 
2 tbsps English mustard 
3 tbsps apple cider vinegar 
3 tbsps Worcestershire sauce 
½ tsp chilli powder 
1 tsp salt 
½ tsp black pepper 

Method
In a saucepan, add the Guinness and bring it to a boil - note here that it will really foam up, don’t worry about it, just stir from time to time. Once boiling reduce the heat to medium, add the sugar and stir.   Leave the mixture so it is simmering. 

In a separate bowl mix together the ketchup, mustard, vinegar, Worcestershire sauce and chilli powder.  It is important to really mix here.  Once fully mixed take a couple of large spoonfuls of the hot liquid and mix through the ketchup mixture.  Add the ketchup mixture to the Guinness mixture and thoroughly stir.  Season with salt and pepper and cook for 15-20 minutes until the mixture is a little thicker.  The mixture will thicken as it cools so don’t worry too much.   

Before turning off the heat check the sauce, it needs a little acidic bite, needs to not taste too sweet and should be balanced.  If too sweet or not enough acidic bite add another tbsp of vinegar and Worcestershire sauce. 

The sauce is ready immediately to use.  Pour any leftover sauce into a sterlised jar and keep in the fridge.