Black Bean and Sweet Potato Burgers with Spicy Mayo

Preheat oven to 400°F (200°C). Toss the cubed sweet potato with olive oil and roast on a baking sheet for 20-25 minutes, or until tender. Let cool slightly.

In a large bowl, mash the cooked sweet potato with a fork or potato masher. Leave some chunks for texture.

Add the rinsed and drained black beans to the bowl. Mash about half of the beans with the sweet potato.

Add the chopped red onion, breadcrumbs, chili powder, cumin, garlic powder, salt, and pepper to the bowl. If using, add the egg.

Mix all ingredients thoroughly until well combined. If the mixture is too wet, add more breadcrumbs. If it's too dry, add a little water or more mashed sweet potato.

Form the mixture into 4 patties.

Heat a tablespoon of olive oil in a skillet over medium heat. Cook the patties for 5-7 minutes per side, or until golden brown and heated through. Alternatively, you can bake the patties on a baking sheet at 375°F (190°C) for about 20 minutes, flipping halfway through.

While the burgers are cooking, prepare the spicy mayo: In a small bowl, combine the mayonnaise and sriracha. Adjust the amount of sriracha to your desired level of spiciness.

Toast the burger buns.

Assemble the burgers: Spread spicy mayo on the top and bottom buns. Add lettuce, tomato slices, and the black bean and sweet potato patty. Serve immediately.