Preheat oven to 400 F. Line baking sheet with aluminum foil and set aside.
Make chimichurri: In a small bowl combine chimichurri ingredients. Stir to combine and set aside to allow flavors to meld.
Make cauliflower steaks: In a pinch bowl combine salt, pepper, and garlic powder. Stir to combine and set aside. Place head of cauliflower stem side down on cutting board. Cut head in half, then cut each half into slices. Save and reserve any florets that break off for future dishes. Sprinkle both sides of each steak with spice mixture.
In a fry pan warm coconut oil and olive oil. Place steaks in pan, working in batches as necessary, and fry for 3 minutes on each side or until golden and caramelized.Transfer steaks to oven to finish cooking for an extra 10-15 minutes, until the steaks are tender and crisp on the edges.
Serve cauliflower steaks hot from oven with a healthy spoonful or two of chimichurri on top.