Preheat the oven to 450°F.
Cut the zucchini in half lengthwise, then score them diagonally in a crosshatch pattern.
Set the zucchini on a plate and sprinkle with salt. Let them sit for 20-30 minutes (this helps remove excess moisture).
Use a paper towel to dab the moisture from the zucchini.
Heat a large cast iron skillet or stainless steel pan (make sure it's oven-safe) over medium heat. Add the avocado oil and cook the zucchini face down for 5-6 minutes, then transfer it to the oven and let it roast for 5 more minutes.
Flip the zucchini and let it roast another 5 minutes. Remove.
To make the sauce, add the Greek yogurt, feta cheese, garlic, fresh mint, lemon juice and zest, plus a pinch of salt and pepper to a small food processor. Process the sauce until smooth.
Add the sauce to the bottom of your serving plate/s, add the roasted zucchini on top, then top the zucchini with more crumbled feta, fresh mint, crushed pistachios, lemon zest and sumac.
