In a large bowl, combine the ground beef, chopped onion, minced garlic, Worcestershire sauce, Dijon mustard, salt, and pepper. Mix well until all ingredients are evenly incorporated.

Divide the mixture into 4 equal portions and shape each portion into a patty.

Heat a grill or skillet over medium-high heat. Cook the burger patties for 4-5 minutes on each side, or until they reach your desired level of doneness.

During the last minute of cooking, place a slice of cheddar cheese on top of each patty and allow it to melt.

While the patties are cooking, lightly toast the burger buns on the grill or in a toaster.

Assemble the burgers by placing a lettuce leaf and sliced tomato on the bottom half of each bun. Top with a burger patty, followed by sliced onions and pickles.

Spread ketchup and mustard on the top half of each bun, then place it on top of the burger.

Serve the British burgers hot with your favorite side dishes.