Preheat oven to 350 degrees. Line two baking sheets with parchment paper, one will be for the beans, and the other for the mushrooms.
Slice mushrooms -- it should yield about one cup total after slicing. Spread them out on one of your baking sheets. Drizzle with olive oil, season with salt and pepper. Place in oven for 12 minutes, or until mushrooms have dried up slightly and are tender.
Drain beans. Spread them out onto the second parchment lined pan. Season with salt, pepper, 1/2 tsp cumin, 1/2 tsp cayenne, 1/4 tsp turmeric. Roast in the oven until beans have dried out slightly - about 12 minutes as well. You can put them in the oven at the same time as the mushrooms, just make sure to watch them so that they don't burn.
Boil water. When water is boiling, cook quinoa - you want a yield of 1 cup , so this is about 1/3 cup of dry quinoa. Let cool once cooked.
While mushrooms, black beans, and quinoa are all cooking, add 1 tbsp of olive oil to a pan. When heated, add onions and garlic and stir fry until translucent.
Once onions are translucent, add remainder of masala spices -- 1/2 tsp cumin, 1/4 tsp turmeric, and 1/2 tsp cayenne, plus salt and pepper. Stir fry until masala spices have cooked - about 4 minutes. Turn off heat and let cool.
When mushrooms are dry and tender and beans are slightly dry (don't stress if the beans aren't completely, we are just doing this to remove some of the excess moisture), let cool.
In a medium bowl, combine cooled cooked quinoa, oat flour, and ground flaxseed. Season with salt and pepper.
Add onions to quinoa mixture. Stir to combine.
In a separate bowl, combine mushrooms and black beans. Using a fork or a potato masher, smash the mushroom bean mixture slightly so that about half of it is well mashed, and the other half pieces remain. We want a textured burger so pieces are all good!
Now add black bean/mushroom mixture to bowl of quinoa. Stir to combine.
Add 2 tbsp olive oli to the burger mixture. Stir well to incorporate.
Now, form mixture into patties. I recommend oiling your hands with a bit of olive oil to keep the mixture from sticking to your hands!
Once you've formed all of the mixture into patties (yielded about 10 for me, but you can feel free to make the burgers bigger, or mini!), heat 1 tbsp of olive oil on a skillet, and cook burgers until each side is golden brown and crisp.
Store cooked or uncooked patties in the fridge for a week. Enjoy!