Preheat the oven to 350 degrees.
Grease a cookie sheet with cooking spray or line with parchment paper and set aside. Pulse the beans in food processor until mashed well, or mash manually using a potato masher or fork. Transfer to a mixing bowl and stir in the cilantro, cumin, and oregano. Season with salt, pepper, and cayenne, to taste.
Add breadcrumbs as necessary until the mixture can be handled and isn’t terribly sticky, about ¼ cup. If after ¼ cup it’s still too sticky and difficult to work with, place in the refrigerator for 5-10 minutes.
Shape the mixture into 3 patties. Lightly spray each patty with cooking spray and transfer to the cookie sheet. Place in the oven and bake for 7 minutes. Flip, re-spray, and bake for 7-10 more minutes until crisp on the outside and thoroughly warm. Remove from the oven.
Serve immediately on buns. (Because there is no oil, these patties dry out as they sit so eat them right away.)