Using a sharp knife score the strip loin cross ways being sure not to cut all the way through the fat to the flesh. Rub the fennel and cumin seeds into the scored skin before covering completely in salt and placing onto a large dish and leaving it uncovered in the fridge overnight.
Preheat your oven to 200 degrees Celsius
Meanwhile cut the rhubarb and pears into rough chunks and place them into a large baking dish that can also hold the pork. Remove the pork from the fridge and scrape as much of the salt from the skin as you can using the back of a knife, discard the salt. Place the pork onto the pear and rhubarb along with the stock and verjus. Place the tray into the oven and cook for 50-60 minutes or until crackling is crispy and the pork is cooked to your liking. Remove the pork from the oven and allow it to rest for 10 minutes.
Meanwhile scoop out the pear and rhubarb along with any of the pan juices under the pork and transfer this to a food processor or blender and blitz on high for 1-2 minutes until finely chopped. Adjust the seasoning and serve with the crispy strip loin.