Carefully remove the green leaves from the cauliflower without harming the stem. Cut the cauliflower in half lengthwise through the center. Then, cut a 1-inch/2cm thick steak from each half of the cauliflower. Unfortunately, that's all you get from one head of cauliflower. You can try to cut one more steak from each half, or make cauliflower skewers with the rest of the florets.
Cauliflower Skewers: Cut the rest of the cauliflower head into florets and add them to skewers.
Brush the cauliflower steaks (and skewers if you made some) with olive oil.
Grill each side of the steaks (and skewers) for 5-10 minutes. Serve with chimichurri sauce or season with salt and pepper.