To make the burgers, combine the beef and pork, onion and Worcestershire sauce in a medium-sized bowl. Season with salt and pepper. Shape into 4 even-sized burgers. Put on a plate, cover and refrigerate for 30 minutes.
To make the barbecue sauce, combine all the ingredients except salt and pepper in a small saucepan over medium heat and bring to a boil. Decrease the heat and simmer for 10 minutes or until the sauce thickens. Season with salt and pepper. Transfer to a bowl and set aside to cool.
Preheat a griller (broiler) to high. Preheat a flat grill plate or large frying pan over medium heat. Drizzle with oil and cook the burgers for 4 minutes on each side, for medium, or until cooked to your liking. Meanwhile cut the buns in half horizontally and toast the cut sides under the broiler.
Transfer the burgers onto a tray small enough to fit under the grill. Place the blue cheese on top of the burgers and melt under the grill. Arrange the rocket and tomato on the bun bases. Place the burgers with blue cheese and a few slices of pickled cucumbers on top. Spoon on the barbecue sauce, cover with the lids and serve. Barbecue sauce can be made in advance. Double the recipe to have at hand when required. Store in a sterilized glass bottle or jar in the refrigerator for up to 6 months.
This recipe is excerpted with permission from <a href="http://www.amazon.com/gp/product/1742704514/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=1742704514&linkCode=as2&tag=craftfocom-20">"Great Pub Food: Make Home Your New Local"</a> by Rachael Lane and published by Hardie Grant Books.