Fresh maitake/hen of the woodsabout 1 ounce per burger is fine (this will be three or four thumbs sized clusters)
Kosher salt and fresh ground pepper
Slicesof swiss cheeseabout 1 oz/ is ample
Condiments of your choice. I like mayonnaisemixed some hot sauce or sriracha it's awesome, my ramp ketchup recipe would be good too.
Lettuce. Look for "Boston butter lettuce" at your grocery storeit's a bit more expensive, but juicy and flavorful. Leaf lettuce is a bit weak for me, and romaine has too much body.
Fresh sliced tomatoespreferably heirloom if they are in season, my favorite variety is the yellow taxicab.
Ground beef. Preferably grass fedand the highest fat content available.
Instructions
First clean your maitake. If they are very clean looking, which they can be, simply brush them with a cloth or pastry brush. Pick the mushroom into small clusters about the size of your thumb.
Cut each bun in half, then spread evenly with soft butter as you would a grilled cheese. Toast the buns in a skillet or if cooking for multiple people, a long pancake griddle. When the buns are toasted, reserve them, making sure the toasted sides are facing up. Putting the toasted buns on top of each other while still warm will cause them to steam and lose their crispness. Have your mis-en-place ready, that means your lettuce is washed and picked, and the cheese/tomatoes are sliced and ready to go.
Heat a cast iron skillet until smoking or have a grill hot and ready to go. Sear the maitake in some flavorless oil like grapeseed until caramelized and golden brown, season with salt and pepper and reserve. Season the burgers with kosher salt and pepper and cook either in the cast iron or on the grill until one side is crusted and has a golden brown sear.
Flip the burgers and place the cheese on top, then top with the maitake. To melt the cheese refer to my note below. Allow the burgers to rest for 3-4 minutes, which will allow the juices to redistribute, making the burgers even more tender and juicy. Arrange the burgers on the buns, top with lettuce, sliced tomato, or whatever else you wish.