This is the national dish of Afghanistan. It can be altered a bit, which I've done on occasion. Such as, lamb is traditional, but you can use beef or chicken. Also, you can use dark raisins if you prefer (though golden sultanas are traditional in this dish). And adjust the spices to suit your own taste preferences.
Sauté diced onion in oil until soft and just starting to brown. Add lamb (or chicken) cubes and brown lightly. Add 2 cups of water, 1 tsp salt, cinnamon, cumin, cardamom and saffron. Cover and simmer until meat is tender, about 45 to 60 minutes.
With a slotted spoon, remove meat from the skillet and set aside. Reserve pan juices (for later use). In same skillet, sauté carrots and sugar in oil until lightly browned. Remove carrots from pan; set aside.
In same skillet, add sultanas (or raisins) and cook until they begin to swell and pucker.
Add pan juices to medium saucepan, let come to a boil. Add rice, 1 tsp salt, and enough boiling water to rise 2 inches above the rice level. Let come to a boil, then reduce heat to low and let rice simmer slowly until the water is absorbed and the rice is tender but not mushy.
If using optional nut garnishes, sauté pistachios or almonds in a small skillet over low heat for 3 to 4 minutes or until light golden; set aside.
Preheat oven to 300°F.
Mix the meat, carrots, raisins and rice together. Place in a large oven-proof baking dish. Cover and bake for about 20 to 30 minutes (or up to an hour).
To serve, spoon the meat/rice onto a large serving platter. Garnish with pistachios or almonds (if using). Serve immediately while still hot.