Mince the skirt steak and fat or suet together (see above), place in a large bowl and season with the thyme, salt and plenty of pepper. Use clean hands to mix the meat and seasonings thoroughly and bind the mixture together. Divide the seasoned beef into 4 portions and shape into burgers, each about 125g and no thicker than 2cm.
Slice the cheese and pickled cucumbers thinly. When everything is ready to go, get your fire going; you want a good deep bed of really hot embers. Set a grill over the fire.
Once everything is glowing super-hot, and you can hover your hand above the grill for 1 second at most, lay the burgers carefully on the grill. They should start to sizzle and smoke immediately. Cook for 2–3 minutes on each side. I like to serve the burgers just under medium but you can leave them on a minute or two longer. You need a searing heat, to ensure the burgers take on lots of colour and stay juicy.
A minute or so after turning the burgers, add the bacon to the grill. (At this point you should be able to hover your hand above the grill for a maximum of 4 seconds.) Cook until crisp on both sides. When the burgers are almost done, lay the cheese slices on top and let them melt. (Move the bacon to one side if it’s done.) Pop the burgers into the soft buns with the bacon rashers and pickled cucumbers and serve.