01 - Preheat oven to 425°F. Line a large baking sheet with parchment paper.
02 - Remove outer leaves from cauliflower heads. Trim stem ends while keeping core intact.
03 - Slice each cauliflower head into 1-inch thick steaks, yielding 2-3 intact steaks per head. Reserve loose florets for another use.
04 - Place steaks on prepared baking sheet. Brush both sides with olive oil and sprinkle evenly with smoked paprika, cumin, garlic powder, salt, and pepper.
05 - Roast in oven for 25-30 minutes, flipping gently halfway through, until golden brown and tender with crispy edges.
06 - In a medium bowl, combine parsley, cilantro, oregano, garlic, olive oil, red wine vinegar, and red pepper flakes. Stir well and season with salt and pepper to taste. Let stand at room temperature to develop flavors.
07 - Arrange roasted cauliflower steaks on a platter and spoon chimichurri sauce generously over the top. Serve immediately.