Preheat oven to 400℉. Set a baking sheet with parchment paper.
Put the beets to boil in the water in a medium pot over medium heat until the beets are tender, about 15-20 minutes.
Place the cooked beets into a food processor with the black beans. Process just enough to combine fully. Take them to a bowl and keep them aside.
Start heating the olive oil in a pan or large skillet at medium temperature. Add onion and cook for 2 minutes until onion is soft. Add garlic, stir continuously, and cook for 30 seconds.
Add the beet and black bean mixture with parsley, cumin, oregano, thyme, oat flour, walnuts, liquid aminos, ground flaxseeds, yeast flakes, cayenne pepper, rolled oats, and salt to combine.
Shape into burgers by dividing the burger batter equally. I got about eight burgers and placed them on a baking sheet in a single layer.
Bake for 40 minutes, turning the burgers over halfway. Make sure they are slightly brown on equal sides.