01 - Preheat oven to 425°F and line a large baking sheet with parchment paper.
02 - Remove leaves and trim stems of cauliflower, keeping cores intact. Slice heads into 1-inch thick steaks, reserving any loose florets for later use.
03 - Arrange steaks on the prepared baking sheet. Brush both sides with olive oil. Combine smoked paprika, garlic powder, pepper, and salt; sprinkle evenly over steaks.
04 - Roast for 15 minutes. Carefully flip steaks and roast for an additional 12 to 15 minutes until golden brown and tender.
05 - Combine parsley, cilantro, oregano, and garlic in a bowl. Stir in olive oil, red wine vinegar, red pepper flakes, salt, and pepper. Let stand to meld flavors.
06 - Transfer roasted cauliflower to a platter and spoon chimichurri sauce generously over the top. Serve warm.