In a large bowl add the beef, beer, worcestershire sauce and grainy mustard. Grate your onion over top of the beef allowing juices to fall in and carefully mix together ingredients. Separate into 4 equal balls and lightly press on each ball to form your burger. Put an indent in the middle of your burger and season generously with salt and pepper.
Heat a large nonstick pan over medium-high heat and add a drizzle of olive oil. When the pan is hot add your burgers and cook 4-5 minutes on one side, flip and 4-5 minutes on the other side. Top each burger with a slice of cheese for the last two minutes of cooking, covering with a lid or aluminum foil to help melt the cheese.
Mix together mustard, mayonnaise and a pinch of salt and pepper to make your burger sauce. Spread on top and bottom of burger buns.
Place lettuce and tomato on your bun, top with back bacon, a burger and finish with pickles. Add your bacon skewer to the top of the bun and serve.