Heat a large saucepan of water to 63°C (145°F). Trim any excess sinew from the pork. Season with salt and place each in a small vacuum-seal or zip-lock bag with 2 teaspoons extra virgin olive oil. Follow the Masterclass on sous-vide cooking and cook for 1½ hours.
Preheat the oven to 180°C (350°F/Gas 4). Remove the pork from the bags. Heat the olive oil in an ovenproof frying pan over medium heat. Sear the pork all over, then roast for 4 minutes. Set aside and rest in a warm place. Thinly slice each piece widthways and serve immediately.