½ teaspoon Herbes de Provence or dry Italian seasoning
2 garlic cloves
1 tablespoon soy sauce
454g lean ground beef
Canola oil
1 tablespoon Dijon mustard, plus more for serving
1 cup grated Swiss, Gruyere, or Emmental cheese
2–4 burger buns, plain or brioche, toasted or untoasted
Directions
Place a large cast iron skillet over medium heat. Add in 1 tablespoon of butter along with the onions, season with salt and pepper, and cook down until softened and lightly golden, about 5 minutes. Add in the remaining butter along with the mushrooms and dried herbs, turn the heat up to medium-high, and cook for 5 to 7 minutes or until deeply golden. Add in the garlic and soy sauce and cook just until the soy sauce has reduced, about 30 seconds.
Remove the mushroom mixture from the pan and set aside.
Add a splash of oil to the pan and turn the heat up to high. Divide the beef into four equal portions and shape each into a ball. Season well with salt and pepper and add to the pan. Using a spatula, firmly press the burgers down until quite flat and cook for 3 to 4 minutes or until well seared.
Flip the burgers over and brush the seared side with the mustard. Continue to cook the burgers for 2 minutes or until cooked through.
Add on the mushrooms and divide over the cheese. Cover the pan with a lid and allow the cheese to melt. Serve the burgers on the buns with extra mustard. If serving 2 extra hungry people rather than 4, stack two mushroom and cheese topped burger on the buns.
