Start by preparing the onion, garlic, bell pepper and mushrooms. Drizzle a medium frying pan with olive oil and cook the veggies over medium heat for 3-4 minutes until softened. Set aside to cool.
Preheat the oven to 375F and line a baking sheet with parchment paper.
To a medium bowl, add the drained and rinsed black beans, the whisked egg, apple cider vinegar, BBQ sauce, spices, salt & pepper and chopped chipotle peppers. With a potato masher, mash the mixture until the black beans are mostly broken down and mixed with the other ingredients. Alternately, you can blend the mixture in a food processor.
Once mashed, mix in the cooled veggies and oat flour. Allow the mixture to sit for a few minutes to thicken up.
Scoop approximately 1/3 cup of mixture and form into pucks with your hands. Place it on the parchment lined baking sheet and gently press down on top to flatten them slightly. The mixture will be very wet, but one formed, the patties should hold their shape on the baking pan. If not, add more oatflour as needed to get a thicker consistency.
Repeat with the remaining mixture, you should get 6 patties.
Transfer the pan to the oven and bake for 15 minutes. Remove and flip the patties and bake for another 10 minutes.
They should be slightly golden brown and crispy on the outside. Allow to cool for 10 minutes. Serve with burger buns and desired toppings, enjoy!