(Makes 4 sandwiches)
1 lb ground beef (I used 85/15 lean to fat ratio)
1 tablespoon worcestershire sauce
• Cracked black pepper
¼ teaspoon onion powder
¼ teaspoon garlic powder
¼ teaspoon paprika
• Olive oil or canola oil
2 medium onions, halved and sliced thinly (semi-circles)
7 ounces shiitake mushrooms, sliced
8-16 slices Havarti cheese (depending on size of bread)
8 slices sourdough bread, lightly buttered on one side
-Place the ground beef into a large bowl, and add to the worcestershire sauce, ½ teaspoon of salt, ¼ teaspoon of the freshly ground black pepper, the onion and garlic powders, and the paprika; mix the seasoning thoroughly into the meat; divide the meat into 4 equal portions (4 ounces each), and shape the portions into flat, oval/rectangular patties that roughly match the shape of your sourdough bread (perhaps a little bigger as the patties will shrink during cooking); place the patties on a plate, cover with plastic wrap and set aside for 20 minutes to allow the seasoning to penetrate and flavor the meat.
-While the patties rest, place a large, non-stick skillet over medium-high heat, and add in about 2 tablespoons of oil; add in the sliced onions plus a couple of pinches of salt and pepper, and caramelize the onions until a deep, golden-brown, for about 10 minutes; spoon the onions into a bowl and cover to keep warm; set aside for a few moments.
-In the same non-stick skillet set over medium-high heat, add another 2-3 tablespoons of oil, and add in the sliced shiitakes mushrooms; saute those until a deep, golden-brown, for about 6-8 minutes; spoon the mushrooms into a bowl and cover to keep warm; set aside for a few moments.
-To cook the patties, use the same non-stick skillet and place it over medium-high heat; add a drizzle of oil into the pan, and once hot, add two of the patties (or however many fit comfortably into the pan) and cook for a couple of moments on that first side; next, flip the patties over and cook a little longer, until the patties are cooked to your liking; remove the patties onto a plate, and loosely cover with foil to keep warm, and repeat the process with any remaining patties; clean out the skillet.
-To assemble and finish the sandwiches, place 1-2 slices of Havarti cheese on the side of the bread that is not buttered, and over that, add about ¼ of the caramelized onions and sauteed mushrooms over the cheese; next, add a patty, another 1-2 slices of cheese over the patty, and cover with another slice of bread with the buttered side up; once all sandwiches are assembled, place the skillet over medium-high heat, and once hot, add a couple of the sandwiches to the pan (buttered-side down), pressing down on them with a spatula to help everything to melt together better, and allow the sandwiches to become toasted and golden on the first side, and then gently flip, pressing down again, and allow them to toast on the other side until the cheese is melty (cover the pan if necessary to help the cheese to melt); repeat the process with the remaining sandwiches; to serve, cut the sandwiches in half, and serve while hot.