Preheat oven to 350 degrees F and line 2 large baking sheets with parchment paper or silicone mats.
In a large mixing bowl, add black beans, corn, pepper, cilantro, red onion, cumin and salt; stir well to combine.
Build each quesadilla: on a half of tortilla sprinkle 3 tbsp (half of 1/3 cup) of cheese, spread 1/2 cup veggie mixture and sprinkle with remaining 3 tbsp of cheese. Fold the other half of tortilla on top pressing on it somewhat gently-hard making a half moon shape. Repeat and make 8 quesadillas. If you have any leftover veggie mixture, eat it.
Bake for 20 minutes. Remove from the oven, let rest for 3-5 minutes and cut each quesadilla in half using serrated knife. Serve with salsa and yogurt.
Notes
Store: While quesadillas taste best fresh, leftovers can be refrigerated up to 2 days.
Make ahead: Refrigerate filling mixture without salt covered for up to 2 days, then make quesadillas.
Freeze: Assemble, then wrap in plastic wrap as tightly as possible without compromising shape. Lay flat in a gallon size Ziploc bag, squeeze air out, seal and freeze up to 3 months. Bake from frozen at 350 degrees F for 25-30 minutes. Or cook in a panini press.
Folding trick for health reasons: I prefer to fold one tortilla in half rather than stack two on top of each other. That way even less cheese is required and veggies are not falling out all over the plate.