Place apricots in heatproof bowl; pour the 2 1/2 cups boiling water to cover over apricots and allow to soak for 1 to 2 hours.
Meanwhile, melt 2 Tbsp butter over low heat in large, heavy skillet and slowly cook onions until caramelized and nicely golden in color, stirring occasionally, about 30 minutes or more. (Don't rush this process, or risk the onions taking on a bitter taste from being cooked too fast and becoming burned rather than caramelized.)
Melt remaining 1 Tbsp butter in another skillet over medium-high heat and sauté cubed lamb until nicely browned on all sides.
Add the browned lamb, coriander, cumin and cinnamon to the caramelized onions and cook, stirring constantly, for 2 minutes; next add the apricots and the water in which they were soaked. Season to taste with salt and pepper. Bring to a boil, cover, and reduce heat; simmer for 1 1/2 hours or until fork tender, stirring occasionally. Serve with hot cooked couscous or long-grained rice.Makes 6 to 8