In a large bowl, combine cooked black beans, grated onion, minced garlic, diced chipotle peppers, adobo sauce, tamari, balsamic vinegar, ground cumin, sea salt, and black pepper. Stir until all ingredients are well incorporated.

Using a potato masher or a fork, mash the mixture until it holds together with some visible chunks of black beans remaining.

Crack in the large egg, mixing it thoroughly until evenly distributed. Sprinkle the panko bread crumbs into the bowl and stir until well combined.

Shape the mixture into six equal patties. Refrigerate if the mixture feels too wet.

Heat a skillet over medium heat, add olive oil, and cook patties for about 5 minutes on each side.

If grilling, preheat the grill, brush patties with oil, and grill for approximately 8 minutes on one side before flipping for 4 additional minutes.

Serve patties on toasted buns with desired toppings.