Preparation:

Preheat oven to 350 degrees F. In a bowl, mash the beans and add salsa. Place the tortillas on two separate baking sheets, then spread the bean mixture onto the tortillas. Sprinkle with cheese and cover with the remaining flour tortillas. 

Place in oven and bake for 15 minutes, or until the tortillas become crisp (may take 18 to 20 minutes depending on your oven). 

While quesadillas are baking, prepare avocado: Peel and pit avocado and mash in a bowl with lime juice. Season with salt and pepper and adjust lime juice if necessary (not all limes yield the same amount of juice). 

When quesadillas are finished baking, remove from oven and cut into wedges. Top each quesadilla with equal parts avocado and yogurt.