Start by preparing the dipping sauce. In a medium bowl mash avocado until creamy and stir in yogurt, garlic powder, and season with salt. Set aside.
Quesadillas. In a medium pan (over medium heat) heat a little bit of olive oil (don’t overdo the oil as tortilla absorb a lot of liquid) and saute onion, garlic, and chili. Follow with black beans and corn, stir well, and cook for a few minutes. Season with salt and pepper and remove from heat.
In the same pan over medium heat add one tortilla at a time. The Half-moon technique works pretty well here. Just spread your filling over half of the tortilla (holding up the other half with your fingers), then fold the other half over the filling. Flip the quesadilla, slide a spatula under the open side, then flip the quesadilla over on the fold. Cook for half to one minute more until golden brown and slightly crispy. Your cheese will be perfectly melted, too.
Repeat with other tortillas.
When all cooked, cut each quesadilla in half and serve immediately.
Drizzle with lime juice, dip in avocado sauce and enjoy!