Heat the oil in a large pan.Add the onions and fry until they are a golden brown ( about five minutes). Stir in the lamb and brown it, stirring often.
Pour some water in the pan, enough to cover the meat and simmer for about 4o minutes.
Stir in the pistachio and almonds and simmer for another 15 minutes.
Meanwhile with a mortar and pestle, grind the saffron threads with the 2 tablespoons of sugar and add some hot water and mix it till it becomes reddish.
Add the saffron liquid and barberries to the pan and stir to combine. Simmer for another 7-8 minutes and remove from heat.
Season with salt and pepper. Serve immediately spooned over plain rice.
