01 - Preheat the oven to 400°F. Line a baking sheet with parchment paper.
02 - Remove any tough outer leaves from the cauliflower and trim the stem so the head sits flat.
03 - In a small bowl, whisk together olive oil, cumin, smoked paprika, turmeric, coriander, garlic powder, salt, and black pepper.
04 - Place the cauliflower head on the baking sheet. Brush generously with the spiced oil mixture, ensuring the marinade covers the entire surface and gets into crevices.
05 - Roast for 55–65 minutes, or until the cauliflower is deeply golden, tender when pierced with a knife, and slightly crisp on the edges.
06 - In a bowl, whisk tahini, lemon juice, minced garlic, and salt. Gradually whisk in cold water, 1 tablespoon at a time, until smooth and pourable.
07 - Transfer the roasted cauliflower to a serving platter. Drizzle generously with the tahini sauce. Garnish with chopped parsley, toasted sesame seeds, and lemon wedges.
08 - Slice into wedges to serve.