In a large bowl, mash the black beans with a fork until mostly smooth.
Add the garlic, olive oil, quinoa, sweet potato, mushrooms, onion, smoked paprika, cumin, oregano, salt and pepper. Mix until well combined.
Divide the mixture into 4 equal parts and shape into patties.
Heat a grill over medium-high heat. Grill the burgers for 5-7 minutes, flipping once halfway through, until slightly charred and warmed through.
In a small bowl, whisk together the balsamic vinegar, honey, and Dijon mustard until combined.
Brush the glaze on the burgers and cook for 1-2 minutes.
Serve the burgers on buns with desired toppings.