Mix the crushed garlick, sweet soysauce, tomatosauce, salt and pepper, in a small bowl, all off equell portion, about 2 tablespoons each.spread over the lamb, heat the oven to 180 C and put in lamb for 3 hours. But, after 2 hours, put in your patatoes, carrots, onions, kumera′s(sweet patato) and pumkin, so it can also roast with the fat , for the last hour, untill all will be ready together, and then take the lamb, carve up to slices, put the vegetables in a seperate dish. Keep warm. Make a gravy from the drained meat, but drain out the fat first.To make the gravy, use some gravypowder, or flour and water, bring to a boil, then put in a seperate bowl.