01 -
In a skillet set over medium heat, cook bacon strips until crisp. Transfer to paper towels to drain.
02 -
Pour off excess bacon fat, leaving a thin layer in the pan. Add sliced onions and cook, stirring occasionally, until deeply caramelized, about 10 to 15 minutes. Pour in Irish stout and simmer, stirring occasionally, until liquid is reduced by half. Season with salt and black pepper.
03 -
In a mixing bowl, combine ground beef with Worcestershire sauce, salt, and pepper. Mix gently to incorporate. Shape into four uniform burger patties.
04 -
Preheat a grill or skillet to medium-high heat. Place patties on the hot surface and grill for 3 to 4 minutes per side, flipping once. Sprinkle with cheddar cheese during the last minute and allow cheese to melt.
05 -
In a small bowl, whisk together sour cream, Dijon mustard, and a pinch of salt until smooth.
06 -
Generously spread butter onto the cut sides of brioche buns. Toast, buttered side down, in a skillet or on the grill until golden brown.
07 -
Arrange each bottom bun with a cooked beef patty, a portion of caramelized onions, two slices of bacon, and a generous spoonful of sauce. Finish with the top bun.