Roast Rib of Beef Stuffed with Smoked Oysters, with Chilled Cucumber Sauce

Although I eat less meat than I used to, a large piece of rare roast beef remains one of my favourite treats. I particularly like this way of roasting it, as the oysters add a mild and irresistible smoky flavour to the meat, it is a simple idea which I thought up years ago but which, combined with the refreshing sauce, I find hard to improve upon.