Place sweet potato on a small baking sheet lined with aluminum foil. Bake for 35–45 minutes, or until tender. Cool slightly, then remove skin, transfer to a small bowl, and mash with a fork or potato masher until smooth.
While potato is cooking, heat oil in a large skillet on low heat. Add onion and cook until just starting to caramelize, about 45–60 minutes. Add chorizo (if using) and cook for 5 minutes. Stir in kale and continue to cook until wilted. Season with salt and pepper.
Combine black beans and paprika in a small bowl.
Divide sweet potatoes, caramelized onion mixture, and beans evenly onto one half of each tortilla, leaving about ½ inch of space along the edges. Fold empty half onto the half with filling.
At this point, you can cook your quesadillas however you prefer. I like to cook mine on a grill sprayed with olive oil and heated at medium. You can also use a quesadilla maker if you have one or cook them in a skillet on medium-high heat, flipping over after tortilla begins to brown.
Cut into wedges and serve with salsa.
Prep time includes time spent baking the sweet potato and caramelizing the onion. Yes, it takes a long time for both, but it's worth it! For a quicker dinner, caramelize the onions and roast the sweet potato the night before.