Begin by removing the cauliflower leaves and set to one side.
Next heat your oil and butter in a large frying pan and once hot add the cauliflower steaks and leaves (you maybe have to do this in batches). Add your seasoning and cover with a lid or foil and cook for 3-4 minutes over a medium to low heat. The aim is to part cook the cauliflower before finishing it on the barbecue. Once they begin to slightly soften remove and set to one side. These are now ready to place on the barbecue for about one minute on each side. Drizzle the cauliflower leaves with oil, add seasoning and place on the barbecue also. These will take just a few moments to cook so keep a close eye on them.
For the ends of the cauliflower or any bits that don’t make it into the steaks, cook for a little longer until soft in the same pan with butter and oil, covering with a lid and add this to the pea puree mixture once soft so not to waste any of the cauliflower.
For the pea puree, simply add the cooked peas and all other ingredients (plus leftover cauliflower) to a nutribullet or blender and blitz until you have a smooth paste. You can add a splash of water or vegetable stock to loosen further if you prefer.
Place a small dry frying pan over a medium heat and add hazelnuts, give the pan a shake every minute or so until all sides are golden. Remove and roughly crush ready to garnish with.
Next add a glug of oil to the same pan and once the oil is hot (test by using one sage leaf to begin with, it should fizz immediately) then add in the handful of sage leaves and cook until crispy.
Serve the cauliflower steaks on a generous helping of the pea puree and serve while the cauliflower is hot. Add extra seasoning to taste, plenty of lemon zest and garnish with both the hazelnuts and sage leaves.