MAKE THE TAHINI RANCH: In a medium bowl, whisk together the Greek yogurt, buttermilk, tahini, lemon juice, dill, chives, onion powder, garlic powder, garlic clove and kosher salt. Set aside.
PREPARE THE CAULIFLOWER: Preheat the oven to 450°F. On a sheet pan, toss the cauliflower with the olive oil, Aleppo pepper and salt to coat.
Roast, tossing halfway through, until the cauliflower is golden and tender, 30 to 35 minutes. Transfer to a platter and drizzle with the tahini ranch. Garnish with the chopped herbs and serve.