Preheat the oven to 200°C/400°F/gas mark 6.
Place all the marinade ingredients into a food processor or mini blender and blitz until coarse but spreadable.
Remove the leaves from around the cauliflower, but don’t remove the bulb at the bottom, as this is what will keep your steaks intact. Halve the cauliflower and, working from the cut side out, slice each steak around 1½ cm thick … you will probably only get two full steaks from each half but you can roast the remaining florets in the same way.
Generously brush the steaks with the marinade. If you want to do this ahead of time, you can leave them to marinate in the fridge until you need them.
Place the steaks on a roasting tray and loosely cover with foil. Roast for 15–20 minutes before removing the foil for a further 10 minutes, turning once.
Heat a griddle pan to a medium-high heat and finish the steaks off in the pan to mark/sear on both sides. Serve with your chosen accompaniment.