We begin by preparing the lamb, which we will have already purchased, duly portioned into quarters, one with the shoulder and half of the rib-the front part- and another with the leg and the other half of the rib, the back room. With a clove of garlic, peeled and cut in half, we are rubbing the lamb meat vigorously so that it is impregnated with its flavor.
Next, salt slightly and add in each quarter half a nut of lard, massaging well to cover the entire surface of the skin. Peel the potatoes and cut them into irregular pieces. On this occasion, instead of looking for bakery-type potatoes, we have made larger pieces since they are going to cook all the time with the lamb, collecting its juices and flavors.
Arrange the potatoes in the baking dish and place the quarter of lamb on top of them. Add a glass of water, a splash of vinegar and cook at 180ºC. Every half hour, we turn the lamb and take the opportunity to water it well with its sauces. We do the same with the potatoes, turning them so that they cook everywhere.
When the lamb has a nice color, we add half a glass of water and another little vinegar, turning it over for the last time. We raise the oven temperature to 200ºC and continue baking until we like the color. With a wooden spoon, we scrape the juices from the tray, deglazing, so that they integrate with the sauce. We bring to the table.