Drain and rinse the beans very well. Either combine all ingredients in a food processor or mash with a fork until evenly mixed. For non-mushy burgers, stop mashing before the mixture is completely smooth. Form into patties (add a little flour if needed). Either fry - flipping halfway through - or bake on a parchment-lined pan at 350 F for 10 minutes, flip, then bake an additional 10 minutes. (For grilled black bean burgers, see grilling instructions listed earlier in this post.) Leftover burgers can be refrigerated or frozen in meal prep containers for a later day.