Preheat Oven and Prepare Vegetables: Position a rack in the center of your oven and preheat to 425°F (220°C). In a large mixing bowl, combine the diced red bell pepper, zucchini, and red onion. Drizzle with olive oil and sprinkle with oregano, smoked paprika, and black pepper. Toss until the vegetables are evenly coated.
Roast the Vegetables: Spread the seasoned vegetables in a single, even layer on a rimmed baking sheet. Roast for 20-25 minutes, tossing halfway through, until the vegetables are tender and have developed caramelized edges.
Prepare a Garnish: While the vegetables are roasting, place the crumbled feta in a small fine-mesh sieve. Rinse under cold running water for about 30 seconds. Shake gently to remove excess water and set aside.
Warm the Pitas: About 5 minutes before the vegetables are finished, warm the pita breads. You can toast them lightly in a toaster or place them directly on the oven rack for 2-3 minutes until warm and pliable.
Assemble the Pitas: Carefully slice each warm pita in half to create two pockets. Spread about 2 tablespoons of hummus evenly on the inside of each pita half. Fill each pocket with a generous amount of the roasted vegetables, then tuck in a handful of the fresh spinach and arugula blend.
Serve: Squeeze a wedge of fresh lemon juice over the fillings in each pocket. Top with the rinsed feta cheese and a sprinkle of fresh dill. Serve immediately.