Pat the steak dry with kitchen paper, rub all over with the Dijon mustard then season generously. Heat a large frying pan and add a splash of olive oil, heat to a high heat and cook the steak on each side for 2 minutes to sear. Use the bone as a handle and sear all around the edges too, until it’s there’s a lovely golden crust all over the meat. Transfer, still in the pan, to the oven and continue to cook for 20 minutes, turning half way through. For medium rare steak use a meat probe and when the centre of the steak reads 55c, it’s done. Remove from the oven and set aside on a board to rest for 10 minutes.
Meanwhile, put the pan back on a medium heat and add the butter with another splash of oil. Add the garlic cloves and thyme sprigs and cook gently for 5 minutes until the pan juices and butter are fragrant and infused.
Carve up the steak and pour over the garlic and thyme butter.
