Preheat the oven to 400°F.
Heat the olive oil in a large skillet over medium heat.
Once hot, add the mushrooms, bell pepper, onion, and garlic to the skillet. Cook for 4 to 5 minutes or until they are starting to brown.
Carefully blot the veggies with a paper towel to remove a bit of their moisture.
Add in the paprika, cumin, and salt. Cook for another minute until fragrant.
Transfer the black bean burger mixture to a food processor along with the black beans and oats.
Pulse for 30 seconds until well combined but not pureed.
Form the mixture into 6 burger patties and arrange them on a baking sheet.
Lightly brush the patties with oil and bake them for 30 minutes, flipping halfway through.
Assemble the vegan burger patty with buns, an onion slice, tomato slices, and lettuce. Serve with your favorite condiments!