Preheat the grill to medium-high heat. In a bowl, toss the zucchini slices with olive oil, salt, and pepper until well coated.
Place the zucchini slices on the grill and cook for about 3-4 minutes on each side, or until grill marks appear and the zucchini is tender. Remove from the grill and set aside.
In a medium saucepan, bring the vegetable broth or water to a boil. Add the orzo pasta and cook according to package instructions, usually about 8-10 minutes, until al dente. Drain and set aside.
In a large mixing bowl, combine the cooked orzo, grilled zucchini, crumbled feta cheese, and basil pesto. Gently toss until everything is evenly mixed.
Add the halved cherry tomatoes and toss again. Adjust seasoning with salt and pepper if needed.
Serve warm or at room temperature, garnished with fresh basil leaves if desired.