For the smash burgers

• Place chopped mushrooms and ground beef into a large bowl.
• Sprinkle with salt and form into 4 large balls (or 5-6 smaller ones, which means of course you'll need more buns and toppings!).
• Fire up your grill for medium-high heat. Place a griddle or a large cast iron pan over the highest heat.
• Add the oil and spread out a bit.
• Place the balls of beef on the griddle and let cook for one minute. Just let them cook, don't mess with them.
• Take your press and flatten out the patties. I like to use the point of the press and work my way around the ball first, doing a little section at a time and then, finally, I press down on the entire patty to flatten it out. You can also just flatten out the ball all at once. At this point I also like to season the patties some more.
• Let the patties cook until you start to notice a little char along the edges. Flip, season again if desired, and continue cooking another minute or so until the other side is charred. The burgers are thin so they will cook very quickly so watch out.
• Top patties with cheese and let cook another 30 seconds to melt the cheese.
• Toast the buns. Remove, add the patties.
• Add remaining ingredients to assemble the burgers.
• Devour immediately.