Preheat oven or toaster oven to 300F°. Line a baking pan with parchment paper.
Prick sweet potato with a fork and place in microwave. Cook for 2 - 3 minutes, until tender. Allow it cool and then cut it into cubes. Set aside.
In a food processor add the walnuts, nutritional yeast flakes, oats, flaxseed, and salt. Pulse until a course flour forms. Add the cubed sweet potatoes, chopped onion, miso paste, and cooked quinoa. Pulse again. Then use a spatula to push down contents on the side of the bowl. Repeat pulsing and spatula process until everything is combined, leaving some texture. Make 6 patties.
Place a skillet over medium heat, add the olive oil.
Place the patties in the skillet. I use the spatula to shape them a little more at this point as well. Sprinkle the top of the uncooked patty with a little salt and pepper. Allow the patties to cook until brown on the bottom side, roughly 3 – 5 minutes. When they’re ready, flip the burgers and allow the other side to cook.
Place cooked burgers on prepared pan and bake for 10 minutes.
Make aioli by combing ingredients in a small bowl and stir vigorously until well-combined.
To make burgers, place them on buns or serve them on a plate. Top with your favorite toppings including aioli.
Store burgers in an airtight container in the fridge for up to 4 days. These can be froze for up to 1 month.