Place the black beans, mushrooms, and 1/2 cup onion onto a parchment lined baking sheet and roast for 20 minutes. Once they are done allow them to cool before handling.
Process the brown rice, mushrooms, onions, with remaining ingredients in a food processor until it comes together in a ball, but don't overprocess.
Use a burger press to form the patties, this helps them stay together. Form the mixture into a ball and then press.
Refrigerate the patties for a half hour.
Remove the veggie burgers from the fridge and bake in a 350 degree F preheated oven for 20 minutes. This will cook the burgers inside and darken the burgers, but not sear them.
Once the burgers are finished baking place them on a hot cast iron skillet with a little cooking oil and sear the burgers for 3-5 minutes per side.
Top burgers as desired and enjoy!
• Avoid the canned taste of beans by making the black beans at home, try our Pressure Cooker Black Beans.• Only use the mushrooms caps, not the stems, as they are fibrous.• Do not swap regular flour for the vital wheat gluten, this is a necessary binder and helps form a sturdy veggie burger.• If you cannot use liquid soy aminos liquid coconut aminos is an excellent alternative.• It's important to let the patties rest and come together in the fridge and also cook in the oven.