Preheat the oven to 400°F (200°C). In a large bowl, combine the zucchini, bell pepper, eggplant, and red onion with olive oil, oregano, salt, and pepper. Toss until the vegetables are evenly coated.

Spread the vegetables in a single layer on a parchment-lined baking sheet. Roast for 18 to 20 minutes, turning them halfway through. They should be tender, with lightly browned edges and soft centers.

While the vegetables roast, slice the rolls in half. Place them cut-side down in a dry skillet over medium heat and toast for 2 to 3 minutes. The surface should become golden and crisp while the inside stays soft.

Spread hummus generously over the bottom half of each roll. Divide the roasted vegetables evenly among the sandwiches.

Sprinkle with feta cheese and fresh basil leaves. If using, add a light drizzle of balsamic glaze for extra depth.

Close the sandwiches and gently press them together. Slice in half if desired and serve while the vegetables are still slightly warm.