In a pan, preheat 2 tablespoons of olive oil over medium low heat and add sliced onions. Once the onions become translucent, add a few pinches of salt and cracked black pepper. Continue cooking until onions caramelize. This may take up to an hour depending on preference and patience. Stir every 5 to 10 minutes. Periodically add a few tablespoons of water to the pan if the onions start to stick. Once the onions are thoroughly cooked, season them with chipotle pepper.
Remove the onions from the pan and set them aside. Increase the heat to medium high and add 2 tablespoons of olive oil to the pan. Add the sliced mushrooms. Brown the mushrooms for several minutes. Turn them a few times, allowing them to get a crispy golden brown crust. Season them with a pinch of salt, cracked black pepper, cumin and cinnamon. Remove the mushrooms from the pan and set them aside with the caramelized onions.
Build The Quesdilla
Wipe out the pan, and heat on medium high. Add a tablespoon of olive oil. Place tortilla down in pan and quickly layer half of the tortilla with cheese, caramelized onions and sauteed mushrooms, avocado slices, cilantro, and tomatoes. Using a spatula, fold the other side of the tortilla over the cheese and veggies. Press down to make the quesadilla stick. Let cook for 30 seconds and remove from pan. Repeat for the 2 quesadilla.
Cut each quesadilla in thirds and serve with cilantro and lime.