Meat puddings of this type were a large part of middleand working-class cookery. They were easy to make and could be left quite happily gently bubbling at the back of a range for several hours. The meat part-steams, part-boils inside, and as a form of slow cooking, the method is hard to beat. Early steak puddings were often flavored with oysters, rather than kidneys, but as the availability of oysters changed, and because these kinds of puddings are almost infinitely forgiving in terms of ingredients, the secondary flavor became mushrooms, and then kidneys. You can use the same technique for a wide variety of other fillings—pork and apple, sausage and leek—the choice is entirely yours.