The most basic Mongolian eatery is the ubiquitous guanz, or canteen. Guanz are usually found in buildings, gers and can be found in most aimag towns, all over Ulaanbaatar and along major roads where there is some traffic. They usually offer soup, stiutei tsai and either buuz or khuushuur. In the countryside, the ger-guanz is a great way to see the interior of a ger and meet a family, without the lengthy stops and traditions expected with normal visits.
In the countryside most guanz seem to close for dinner (and often lunch as well). In reality, opening hours are often at the whim of staff. The city guanz, which is a good option for budget travellers or people in a hurry, will sometimes masquerade under more alluring names, including tsainii gazar (tea house). Some of the ones on main streets now stay open 24 hours, but the usual hours are 10am to 7pm.
The most restaurants are pretty expensive for the average Mongolian and frequented only during special occasions. Mongolians don't mind blowing an entire week's salary on a good meal, so long as they are enjoying it with friends or family.
Restaurants, usually opens 10am to 10pm daily, are nearly always more hygienic than the guanz and therefore a good choice for children and families. You will probably be assigned an overly attentive waiter or waitress who will polish your silverware to perfection and pour your drinks. In Ulaanbaatar, many restaurants - especially the good ones - will be busy and often full between about 1 pm and 2pm. It pays to get a table before 12.30pm to beat the rush.