Step 1

Saute the mushroom and onion first. Place a medium sized saute pan on the stovetop over medium heat add the oil in it to warm. Remove the stems of the mushrooms and place the caps in a small food processor. Pulse them until they're finely chopped, then add the minced mushrooms to the pan with the oil.

Step 2

While the mushrooms are starting to cook, dice the onion on a cutting board with a sharp knife (you can also put the onion in the mini food processor to dice it) and add it to the pan as well. Stir and cook until both the mushrooms and onion are soft, between 5 and 7 minutes.

Step 3

Once the onions and mushrooms are cooking, take out a medium sized bowl to make the patty mixture in. Use measuring spoons to measure out the rest of the patty ingredients except for the ground meat and add it into the bowl. Use a small whisk to thoroughly mix everything together and set aside to let the flavors combine.

Step 4

When the chopped mushrooms and onions are done cooking, remove them from the heat to let them cool for 3 or 4 minutes, then pour them into the mixing bowl with the seasonings for the patty.

Step 5

Add the ground beef and use your hands to combine everything together. You don't want to work the meat too hard as it will make it spongey when you cook up your burgers, but you want to make sure the mushrooms, onions, and other seasonings are fully incorporated with the ground beef.

Step 6

Separate the beef mixture into four equal portions in the bowl, then wash your hands and take out a sheet pan or platter that's big enough to fit all four hamburgers on it. Place 4 pieces of wax paper (or plastic wrap) big enough to fit the patties on them onto the sheet pan.

Step 7

Take one portion of the meat mixture into your hands and roll it into a ball, then gently start flattening it with your fingers, working your way around the sides and pressing where needed to get a round shape. Make your patty roughly 1/4 inch thick, then place it on one of the pieces of wax paper and repeat the process with the other three portions of meat, washing your hands after you're done.

Step 8

Once all the patties are formed, heat up your grill to between 400F and 425F. Pick the patties up by the wax paper and flip them over onto the grill. Close the lid and cook for 4 minutes, then open the lid and use a spatula to flip the burgers over onto the other side. If adding cheese, cook for 3 minutes then add the cheese and cook another minute or two. If not adding cheese, cook for another full 4 minutes, then check the internal temperature - you want to cook them to an internal temperature of 160 degrees F. If they're not there yet, cook in 2 minute increments with the lid closed until they're fully cooked.

Step 9

Remove the hamburgers from the grill and let them rest for 5 minutes, then serve in a gluten-free bun topped with whatever you like!