Heat oven to 240C/220C fan/gas 9. Rub the beef all over with the oil and season with some salt and lots of black pepper. Transfer to a roasting tray and cook for 20 mins, then turn the oven to 190C/170C fan/gas 5 and roast for a further 10-15 mins per 450g for medium-rare, 15-20 mins per 450g for medium, 20-25 mins for medium-well and 25-30 mins for well done. Remove from the oven and allow to cool.
To make the salsa verde, mix all the ingredients with some salt and pepper. Thinly slice the beef and arrange on a serving platter, drizzle with the salsa verde and rocket leaves and eat with the crusty bread.