Step 1Heat the oven to 350 degrees. Toast the almonds in a shallow baking pan until lightly browned, 7 minutes. Immediately transfer them to a plate and set aside.
Step 2Cut the meat from the bones, discarding excess fat. Reserve the bones. Cut the meat in 1-inch cubes.
Step 3Heat 1 tablespoon of oil in a heavy stew pan. Add the lamb cubes in 2 batches, browning each lightly on all sides over medium-high heat and removing the browned meat with a slotted spoon to a plate. Brown the bones lightly over medium heat, 10 to 15 minutes, and remove.
Step 4Add 1 tablespoon of oil if the pan is dry and heat it. Add the onions and cook over medium heat until light brown, 7 minutes; cover if the pan becomes dry. Return the meat, bones and any juices from the plate to the pan. Add the saffron, salt and pepper to taste and water. Mix well; the liquid will not cover the lamb. Bring to a boil. Cover and simmer over low heat, stirring occasionally, until the lamb is tender, 1 hour and 15 minutes. Remove the lamb cubes and bones with tongs, leaving the onions in the pan. Remove any bits of meat adhering to the bones and add to the lamb cubes. Discard the bones. (For a lighter sauce, refrigerate the cooked meat and its sauce separately for several hours, then skim the fat from the top of the sauce.)
Step 5Bring the sauce to a simmer and add the sweet potatoes. Cover and cook over low heat for 10 minutes. If the sauce is too thin, remove the sweet potatoes with a slotted spoon, leaving most of onions in the pan, and simmer the sauce, uncovered, until it thickens, a few minutes; then return the sweet potatoes to the pan. If the sauce is too thick, add 3 or 4 tablespoons of hot water. Add the ginger, cinnamon, nutmeg, apricots and plums. Cover and cook, gently stirring once or twice, until the sweet potatoes and fruit are tender, about 10 minutes.
Step 6Add the honey to the sauce and stir very gently. Return the lamb cubes to the pan, cover and cook over low heat for 5 minutes. Taste and adjust the amounts of salt, pepper, ginger and nutmeg. Serve hot, garnished with the toasted almonds.