Prep: Start by preheating your oven to 400°F. Grease or line a baking sheet with parchment paper to prevent the patties from sticking.
Grate the Vegetables: Set up your food processor with a grating disc. Cut the sweet potato and red onion into large chunks and grate them using the food processor. Once you’re done, empty the food processor and set the grated mixture aside. If you don’t have a food processor, you can also use a box grater.
Dry Ingredients: Replace the grating disc with a standard S-blade in the food processor. Add the rolled oats, flax seed, garlic powder, cumin, and salt to the processor. Pulse until the mixture forms a fine flour, which should take about 30 to 45 seconds.
Make a Paste: Add one can of the drained black beans, the chipotle peppers, adobo sauce, and avocado oil to the food processor. Process until a thick paste forms, which should take about one minute. Make sure to scrape the sides of the food processor with a spatula as necessary to ensure even mixing.
Combine: Add the shredded sweet potato and red onion mixture to the food processor, along with the remaining can of black beans. Pulse the mixture until it sticks together and is mostly combined. You may need to pause a few times to mix with a spatula to ensure everything is evenly blended.
Form the Patties: To form your patties, it helps to have slightly damp hands. Use a 1/2 cup to portion out the mixture and form 8 even patties. Flatten and smooth out each patty with your hands before placing them on the prepared baking sheet.
Bake: Place the baking sheet in the preheated oven and bake the patties on the middle rack for 20 minutes. After that, carefully flip the patties and then return them to the oven on the top rack. Bake for an additional 15 to 20 minutes. Once done, remove from the oven and let the patties sit on the baking sheet for about 5 to 10 minutes to firm up.
Serve & Store: Enjoy the burgers warm and as desired! I love to serve mine on toasted buns with lettuce, red onion, and chipotle mayo! You can store leftover burger patties in the fridge for up to five days or freeze them for up to two months. They can be reheated in the microwave, toaster oven, or on the stovetop.