Preheat a grill or grill pan over high high heat.
Place the sliced zucchini in a medium bowl. Drizzle with olive oil and sprinkle generously with kosher salt and ground black pepper. Toss with your hands until all the zucchini are evenly coated with oil and salt and pepper (make sure you use a generous amount of oil, or else the zucchini will stick to the grill!)
Add half of the zucchini to the grill (you'll probably need a grill basket) or grill pan. Grill for a few minutes on each side, until the zucchini is nicely charred but just tender. Remove to a large bowl & repeat with the second half of the zucchini.
As the zucchini cools, whisk together the lemon zest, lemon juice, extra virgin olive oil, and fresh mint. Pour over the warm zucchini.
Sprinkle the crumbled feta cheese over the zucchini & toss to combine. Serve warm or at room temperature.