kosher salt and freshly cracked black pepper to taste
Preheat a grill over medium-high heat. Combine the first 7 ingredients in a bowl; toss well to coat. Arrange squash in a single layer on the grill and grill for 5 minutes total, turning halfway through.
Once grill marks appear on both sides and the squash is cooked, remove from the grill and transfer to a serving platter. Slice the zucchini and yellow squash into 1 inch pieces. Crumble the sheet of feta on top, sprinkle with fresh mint and basil leaves and drizzle with the vinaigrette. Adjust salt and pepper as needed and serve immediately.