01 - Preheat the oven to 425°F. Line a large baking sheet with parchment paper.
02 - Remove the leaves and trim the stem of the cauliflower, keeping the core intact. Slice each head into 1-inch thick steaks.
03 - Arrange cauliflower steaks on the prepared baking sheet. Brush both sides with olive oil. Combine smoked paprika, garlic powder, pepper, and salt; sprinkle evenly on both sides.
04 - Roast for 15 minutes, flip steaks carefully, then roast for an additional 12–15 minutes, until golden brown and tender.
05 - In a bowl, combine parsley, cilantro, oregano, and garlic. Stir in olive oil, red wine vinegar, red pepper flakes, salt, and pepper. Mix well and let stand at room temperature.
06 - Arrange roasted cauliflower steaks on a platter and generously spoon chimichurri sauce over each. Serve warm.