Preheat oven to 400°F (200°C).
Cut the cauliflower into 1-inch thick slices.
Arrange the cauliflower slices on a baking sheet and brush both sides with 2 tablespoons of olive oil. Season with 1 teaspoon of salt and ½ teaspoon of black pepper.
Bake for 20-25 minutes, flipping halfway, until the cauliflower is tender and lightly browned.
In a food processor, combine the parsley, cilantro, garlic, red wine vinegar, ¼ cup of olive oil, ½ teaspoon of salt, and ¼ teaspoon of black pepper. Pulse until a smooth chimichurri sauce forms.
Serve the roasted cauliflower steaks with the chimichurri sauce drizzled over the top.
