Start by making the dressing. Add all the dressing ingredients to your blender and blend until smooth. If it seems too thick, add more water or jalapeño juice depending on your preference.
Make your salad. Wash and chop your romaine lettuce, then add to a bowl with rinsed black beans, green onion, cherry tomatoes, cilantro, and red cabbage. Toss with about half the dressing.
Make the quesadillas. Heat a griddle or pan over medium heat. Divide the cheese over 4 tortillas, then top with the other tortilla. Cook for 2-3 minutes per side, until tortillas are browned and cheese is melty. Remove from heat.
Dish tortillas onto plates and use tongs to add salad on top. Top with avocado, extra dressing, and jalapeño slices if desired. Enjoy!