01 - Preheat oven to 425°F. Line large baking sheet with parchment paper.
02 - Remove leaves and trim stem end of each cauliflower, keeping core intact.
03 - Slice each cauliflower vertically into 1-inch-thick steaks. You should get 2–3 steaks per head; save remaining florets for another use.
04 - In small bowl, mix together olive oil, cumin, smoked paprika, coriander, turmeric, garlic powder, onion powder, salt, pepper, and cayenne.
05 - Place cauliflower steaks on prepared baking sheet. Brush both sides generously with spice oil mixture.
06 - Roast for 15 minutes until edges begin to brown.
07 - Carefully flip each steak, brush with remaining oil mixture, and roast for another 15 minutes until golden and tender.
08 - Transfer to serving platter. Garnish with fresh herbs and serve with lemon wedges.