Preheat the oven to 400 degrees F. Prepare a large rimmed baking sheet with parchment paper and set aside.

Remove the green stems and leaves from the bottom of the cauliflower. Place the cauliflower on the prepared baking sheet and use your hands to rub the oil into the cauliflower to coat the entire surface. Sprinkle with chili powder, sea salt and pepper and roast for 30 minutes or until the cauliflower is golden brown and tender. Stick a sharp knife in the center of the cauliflower to ensure it's completely cooked.

Remove the cauliflower from the oven, drizzle with the lemon juice and tahini. Garnish with fresh parsley and lemon zest and serve immediately.