Kebab (also called kebap, kabab and kabob) is a traditional dish of sliced meat originating in the Middle East and later adopted in Central Asia and by the regions of the former Ottoman Empire, before spreading worldwide.
Iranian kabab is served with the basic Iranian meal accompaniments, in addition to grilled tomatoes on the side of the rice and butter on top of the rice.
It is an old northern tradition (probably originating in Tehran) that a raw egg yolk should be placed on top of the rice as well, though this is strictly optional, and most restaurants will not serve the rice this way unless it is specifically requested.
"Somagh", powdered Sumac, is also made available and its use varies based on tastes to a small dash on the rice or a heavy sprinkling on both rice and meat, particularly when used with red (beef/veal/lamb) meat.
At Persian restaurants, the combination of one kabab barg and one kabab koobideh is typically called Soltani, meaning "sultan's feast". The traditional beverage of choice to accompany kebab is doogh, a sour yogurt drink with mint and salt.
In the old bazaar tradition, the rice (which is covered with a tin lid) and accompaniments are served first, immediately followed by the kebabs, which are brought to the table by the waiter, who holds several skewers in his left hand, and a piece of flat bread (typically nan-e lavash) in his right.
A skewer is placed directly on the rice and while holding the kebab down on the rice with the bread, the skewer is quickly pulled out. With the two most common kebabs, barg and koobideh, two skewers are always served.
In general, bazaar kebab restaurants only serve these two varieties, though there are exceptions.
Kabab bakhtiari is a combination of jujeh kabab and kabab barg in a decussate form.
Reference:
http://en.wikipedia.org/wiki/Kebab