Preheat oven to 400 degrees F (200 degrees C). Poke a few holes into sweet potato with a fork; place on a greased baking sheet.
Bake in the preheated oven until sweet potato can be easily pierced with a fork, 35 to 45 minutes. Remove from oven and cool until easily handled. Reduce heat to 350 degrees F (175 degrees C). Spray a baking sheet with cooking spray.
Peel sweet potato and place into a large bowl. Add black beans and mash with a whisk or fork. Add oats, onions, Dijon mustard, cumin, ginger, salt, and cinnamon and mix until well combined. Shape mixture into 6 patties with wet hands and place onto prepared baking sheet.
Bake in the preheated oven until cooked in the center and crisp on the outside, about 8 minutes on each side.