Bring a large pot of salted water to a vigorous boil. Add orzo and cook for 8-10 minutes until al dente. Drain and cool slightly.

In a large mixing bowl, combine the diced red and orange bell peppers, sliced red onion, chopped cucumber, corn, halved tomatoes, chopped basil, and sliced green onions.

In a separate bowl, whisk together olive oil, lemon juice, lemon zest, Dijon mustard, and minced garlic until emulsified. Season with salt and pepper.

Add the cooled orzo to the bowl with mixed vegetables. Drizzle with vinaigrette and gently toss to combine.

Serve immediately, optionally topping with Parmesan cheese.