Cut the sweet potato in half lengthwise, place onto a baking sheet covered with parchment paper, flesh down. Use a fork to pick holes all over the sweet potato skin. Bake for 20-30 minutes or until soft.
Carefully remove from the oven using oven mittens and scoop out the sweet potato flesh. Wait until it is fully cool down before using it in the recipe. You can also prepare the mashed sweet potato a few days before and store it in the fridge.
Make the black bean sweet potato patty batter
Add the cooled and cooked sweet potato flesh into a food processor, 3/4 cup black beans, and process for 15-30 seconds on medium speed to combine and form a mash.
Add rolled oats, flour, onion, all dry spices, and process again for 30 seconds until it forms a thick and sticky batter.
Transfer the burger mixture to a medium bowl and stir in the remaining black beans and some additional vegetables if you like: corn, peas, red bell pepper.
Cover two large baking sheets with parchment paper, lightly oil the paper with avocado oil.
Split the patty batter into 6 even balls and place each ball on the baking paper leaving 4 inches of space.
With your hand palm, press/flatten each ball into burger patty - thickness of your choice. I love mine 1 cm, 0.4 inches thick. The thinner, the crispier, and the faster they cook.
Bake at 400°F (200°C) for 25-30 minutes or until crispy on the sides.
Remove from oven, and serve as a burger patty into a vegan burger bun. I recommend tomato ketchup and Dijon mustard sauce along with avocado slices, tomato slices, and lettuce.
Store in the fridge for up to 3 days in an airtight container. Rewarm in a lightly oiled frying pan or the oven for 8 minutes at 150°C (300°F).
Freeze your vegan black bean patties in an airtight container. Make sure they don't overlap, or it gets difficult to thaw individually. Otherwise, place a piece of parchment paper between each patty to prevent them from sticking together. Rewarm in a hot frying pan or the oven.