Ingredients:

  • 1.5 lbs (680g) ground beef (80/20 blend preferred)
  • 1 tbsp (15 ml) Worcestershire sauce
  • 1 tsp (5g) garlic powder
  • 1/2 tsp (2.5g) onion powder
  • 1/2 tsp (3g) kosher salt
  • 1/4 tsp (1.5g) black pepper
  • 4 burger buns (brioche or pretzel buns recommended)
  • 2 tbsp (30 ml) mayonnaise (optional)
  • 2 tbsp (30 ml) ketchup (optional)
  • 2 tbsp (30 ml) mustard (optional)
  • 1 tbsp (15 ml) olive oil
  • 1 medium yellow onion, thinly sliced
  • 1 lb (450g) cremini mushrooms, sliced
  • 2 cloves garlic, minced
  • 1/4 tsp (1.5g) dried thyme
  • 1/4 cup (60 ml) dry sherry (or beef broth as a substitute)
  • 4 slices Swiss cheese

Instructions:

  1. Heat olive oil in a large skillet over medium heat. Add onions and cook until softened and translucent.
  2. Add the mushrooms and thyme to the pan and cook, stirring occasionally, until the mushrooms are softened and browned and most of the liquid has evaporated.
  3. Stir in the garlic and cook for another minute until fragrant.
  4. Deglaze with sherry (or beef broth), scraping up any browned bits from the bottom of the pan. Simmer until the liquid is reduced to a glaze. Set aside and keep warm.
  5. In a large mixing bowl, gently combine the ground beef, Worcestershire sauce, garlic powder, onion powder, salt, and pepper. Be careful not to overmix!
  6. Divide the mixture into 4 equal portions and form into patties, slightly larger than the buns (they will shrink during cooking). Make a slight indentation in the center of each patty to prevent them from bulging.
  7. Preheat your grill or grill pan to medium-high heat. Alternatively, heat a skillet over medium-high heat.
  8. Cook the patties for 4-5 minutes per side for medium-rare, or longer to your desired doneness. Use a meat thermometer to ensure the internal temperature reaches 160°F (71°C) for medium doneness.
  9. During the last minute of cooking, top each patty with a slice of Swiss cheese and cover the grill or pan to allow the cheese to melt.
  10. Lightly toast the burger buns (optional). Spread mayonnaise, ketchup, and mustard (if using) on the buns.
  11. Place the cheese-covered patties on the bottom buns, top with the mushroom and onion sauté, and finish with the top buns. Serve immediately.