Ingredients:

2 onions, sliced
1 tbsp mustard powder
1 tbsp smoked paprika
1½ – 2kg) pork shoulder, boned with rind attached and tied
140g tomato ketchup
4 tbsp red wine vinegar
1 tbsp Worcestershire sauce
3 tbsp soft dark brown sugar

Heat oven to 160C. Scatter the onions in the bottom of a large roasting tin. Mix the mustard powder, paprika and 1 tsp ground black pepper with a good pinch of salt. Rub this all over the pork. Place the pork, rind-side up, on top of the onions. Pour 200ml water into the bottom of the tin, wrap well with foil and bake for 4 – 5 hrs.
In a bowl, mix the ketchup, vinegar, Worcestershire sauce and brown sugar. Remove the pork from the tin and pat dry. Place the roasting tin on the hob, pour in the ketchup mixture and bubble vigorously for 10-15 mins until thick and glossy. Remove from the heat and pour the sauce into a food processor; blitz until smooth. Smear half the sauce mixture over the meat.
Lift the pork onto a large plate or tray. Remove string and peel off the skin. Using 2 forks, shred the meat into chunky pieces. Add 3-4 tbsp of the barbecue sauce to the meat and toss everything well to coat. Pile into taco shells and serve with extra sauce and some salad.