01 -
Cook turkey strips in a skillet over medium heat until crisp. Transfer to paper towels to drain.
02 -
Sauté the sliced onions in a portion of the remaining fat over medium heat until deep golden brown, about 10 to 15 minutes. Pour in beef broth and simmer until liquid is reduced by half. Season to taste with salt and pepper.
03 -
In a mixing bowl, gently combine ground beef with Worcestershire sauce and a pinch each of salt and pepper. Shape into 4 patties, slightly wider than the brioche buns.
04 -
Preheat grill or skillet to medium-high heat. Sear patties for 3 to 4 minutes per side for medium-rare. Top each patty with grated cheddar during the final minute to allow cheese to melt.
05 -
Stir together sour cream, Dijon mustard, and a pinch of salt in a small bowl until well blended.
06 -
Generously butter the cut sides of the brioche buns. Toast in a skillet over medium heat until golden and crisp.
07 -
Layer the bottom bun with a cheeseburger patty, followed by caramelized onions, two turkey strips, and a spoonful of burger sauce. Top with the remaining bun and serve immediately.