In a skillet, heat the extra virgin olive oil over medium heat. Add the diced yellow onion and chopped baby bella mushrooms. Sauté for about 5-7 minutes, or until the onions are translucent and the mushrooms have released their moisture. Set aside to cool slightly.
In a large mixing bowl, add the rinsed and drained black beans. Using a potato masher or fork, mash the beans until mostly smooth, leaving some chunks for texture.
To the mashed black beans, add the sautéed mushroom and onion mixture, panko bread crumbs, egg, kosher salt, smoked paprika, and Worcestershire sauce. Mix until fully combined. If the mixture feels too wet, add more panko bread crumbs a little at a time until the consistency is moldable.
Using your hands, shape the mixture into burger patties, about ¾-inch thick. Place them on a plate or baking sheet lined with parchment paper.
You can cook the patties on a grill or stovetop. For stovetop cooking, heat a non-stick skillet over medium heat and add a splash of olive oil. Cook the patties for about 5-7 minutes on each side, or until they are golden brown and heated through. If grilling, preheat your grill and cook the patties for about 4-5 minutes on each side.
Serve your The Best Black Bean Burgers on a toasted bun with your favorite toppings, such as avocado, lettuce, tomato, and a dollop of salsa or your preferred sauce.