Wash and dry all produce. Preheat the oven to 450 degrees. Halve, peel, and slice the onion. Halve both zucchini lengthwise and thinly slice into half-moons. Thinly slice the lettuce. Drain and rinse the black beans. Core, seed, and dice the tomatoes.

Heat a large drizzle of olive oil in a large pan over medium-high heat. Add the onion and zucchini. Cook, tossing, for 6-8 minutes, until the veggies have softened. Season with salt and pepper.

Add the tomatoes, Southwest seasoning, and black beans to the pan. Cook, tossing, for 5 minutes, until the tomatoes have softened. Season with salt and pepper.

Using about 2 teaspoons total, cover each tortilla with olive oil. Lay 6 tortillas oil side down on a baking sheet (you may need two baking sheets). Sprinkle the tortillas with half the cheese, top with the filling, and sprinkle with the remaining cheese. Top with the remaining tortillas, oil side up. Bake 3-5 minutes, or until the top tortilla is slightly crispy. Flip and cook 3-5 minutes on the other side, until slightly crispy.

Make the crema: Zest and halve the limes. In a small bowl, combine the sour cream and lime zest.

Finish and serve: Toss the lettuce in a medium bowl with a squeeze of lime juice and a large drizzle of olive oil. Season with salt and pepper. Cut the zucchini and black bean quesadillas into wedges. Serve with the romaine salad and lime crema on the side.