Begin by preheating a large skillet or grill pan over medium heat for about 2-3 minutes.

In a mixing bowl, combine zucchini, red bell pepper, and red onion with a drizzle of olive oil, salt, black pepper, and dried oregano. Sauté the mixture in the heated skillet for 3-4 minutes until slightly softened.

Lay one flour tortilla in the skillet. Sprinkle half of the shredded mozzarella over the tortilla's surface and allow it to heat for about 1 minute until the cheese starts to slightly melt.

Layer the sautéed vegetables, sun-dried tomatoes, kalamata olives, crumbled feta cheese, and any optional greens over the melted cheese.

Top the filling generously with the remaining mozzarella cheese, then place a second tortilla on top. Cook for another 1-2 minutes until the cheese starts to ooze and the tortilla turns golden brown.

Carefully flip the quesadilla using a spatula and grill for an additional 2-3 minutes until golden brown.

Once golden and crispy, remove from the skillet, let cool, slice into wedges, and serve warm with tzatziki or hummus.