In the bowl of a food processor, add herbs, garlic, and red wine vinegar. Pulse to combine. Turn processor on and stream in olive oil. Let run for about 1 minute or until everything is well combined. Place in a bowl and set aside for at least 20 minutes.
Preheat grill to medium heat.
Trim cauliflower and remove the stems and leaves. Cut in half and then cut into 1/2 inch planks. You will extra florets, just place them around the planks when you grill them
Either using heavy duty aluminum foil or a grill safe pan, place your cauliflower on the pan and sprinkle with salt and pepper.
Grill for 3-4 mediums or until both sides are golden brown. Remove from grill and drizzle with chimichurri sauce.