Step 1

Process the dried mushrooms in a food processor, or a clean coffee grinder (grind some raw rice to clean out coffee grinds), until ground into a powder. Remove any large mushroom pieces that didn't grind down, a few small pieces will be fine.

Step 2

Make the burger mixture: In a large bowl, use your clean hands to gently mix together the meat, salt, mushroom powder, black pepper and Worcestershire sauce. Mix just until everything is mostly combined, a minute or two. Do not overwork the meat mixture or it will become tough and meatloaf-like.

Step 3

Form into patties: Shape the meat into 3-4 patties, using about a quarter to a third of a pound per patty, creating a slight indentation at the centers of the patties (this will help keep the patties fairly flat when they cook, as the sides tend to contract more than the center).

Step 4

Sauté the mushrooms, then the onions: Prepare your grill for high, direct heat. While the grill is heating up, heat a large sauté pan over high heat for 1 minute. Add the mushrooms and dry-sauté them until they release their water, about 2-3 minutes.Add the onions and the olive oil, toss to combine and continue to sauté over high heat 1 minute. Add salt to taste and cook until the onions soften and begin to brown. Turn off the heat and place in a bowl.

Step 5

Grill the burgers on high, direct heat to the desired doneness, between 5-8 minutes per side, depending on the thickness of the burgers and how hot your grill is.

Step 6

Add the cheese: When the burgers are almost done, lay the Swiss cheese over them and allow the cheese to melt.

Step 7

Grill the buns: Paint the burger buns with a little olive oil and toast them on the griddle or grill grates.

Step 8

Assemble the burgers: To assemble, put a burger on the bun and top with the sautéed onions and mushroom mixture.