Heat the olive oil in a large skillet. Dust the lamb with flour and place it in the hot pan. Cook over high heat until it begins to color, then add the onions and carrots, saute another minute. Stir in the sugar, pepper, ginger, salt, cinnamon, saffron, and pumpkin; saute 1 minute. Add the broth and lemon juice, simmer for about forty-five minutes or until the sauce thickens slightly and the meat is tender. Stir in the raisins and serve over cous cous or rice pilaf.