Preheat a grill or grill pan over medium-high heat.
Brush the zucchini slices with olive oil and season lightly with salt and black pepper.
Grill the zucchini for 3–4 minutes per side, or until tender with visible grill marks.
Remove from the grill and let cool slightly, then cut into bite-sized pieces.
In a small bowl, whisk together the olive oil, lemon juice, Dijon mustard, honey (if using), garlic, salt, and pepper until well combined.
In a large serving bowl, combine the grilled zucchini, cherry tomatoes, cucumber, red onion, feta cheese, parsley, and basil.
Pour the vinaigrette over the salad and gently toss until evenly coated.
Serve immediately or refrigerate for 15–20 minutes before serving for even more flavor.