1 ½ lbs. 80% lean ground beef
3 tbsp. finely grated white onion (grated over a bowl to catch the juices)
2 tbsp. Worcestershire sauce
Salt and pepper
A drizzle of olive or canola oil
2 tbsp. butter
2 tbsp. flour
½ cup whole milk
½ cup lager beer
1 rounded tsp. (about a squirt) Dijon or English mustard
1 tsp. granulated garlic
¼ tsp. cayenne
1 package (8 oz.) shredded sharp yellow cheddar
Pretzel hamburger rolls, split and warmed
Grainy Dijon mustard
Dill or bread-and-butter pickle chips
Chopped white onion
Heat a large griddle pan or large cast-iron skillet over medium-high.
In a medium bowl, mix the beef, grated onion and Worcestershire; season with salt and pepper. Form 4 large patties (thinner in the centers for even cooking). Drizzle the patties with the oil. Cook for 8 minutes, turning occasionally.
Meanwhile, heat a medium saucepan over medium; add the butter. When it melts, whisk in the our. Gradually whisk in the milk and season with salt. Cook, whisking often, until the sauce thickens, about 2 minutes; slowly whisk in the beer. Add the Dijon, granulated garlic and cayenne. Reduce the heat to low, then add the cheese, a handful at a time, whisking to melt between additions.
Build the burgers by spreading the bun bottoms with the grainy Dijon, then top with some pickles and chopped onion. Top with a few sprigs of watercress, the patties, some cheese sauce and the bun tops.