Hala accepts Kosher prepared food, because it is created in a 'holy' way. To my knowledge though, there are no restaurant chains that are kosher. BTW vegan is kosher.

Kosher food is food that meets Jewish dietary laws, or kashrut, which comes from the Hebrew word for "fit" or "proper." Any food can be called kosher food if it adheres to Jewish law, or halacha. Conversely, foods typically labeled as "Jewish" aren't necessarily kosher. Jewish foods are generally those dishes that are traditionally Jewish. Kreplach, cholent, kugel, latke, and kishka are all traditionally Jewish foods, but if they are not prepared in accordance with kashrut, they will not be kosher food.

The word "kosher" is not only used for food, however. Kosher basically means that something follows all the Jewish legal guidelines. The word has even gained a place in American slang to mean appropriate, legitimate, or proper. Instead of saying "that's not right," one might say "that's not kosher."

Kosher food laws are rather extensive. Some are derived directly from the bible and others through rabbinic interpretations over the years. What are some of the laws governing kosher food?

    * According to the Torah (also known as the five books of Moses, the Old Testament, or the Pentateuch) cloven hoofed, cud-chewing mammals are kosher. Deer, sheep and goats, for example are all kosher, while pig and rabbit, for example, are not.
    * Only certain birds are considered kosher in the United States. This includes chicken, duck, goose, and turkey.
    * Lobster lovers might be dismayed to find that for seafood or fish to be kosher, it must have fins and easily removable scales. Shellfish generally, and lobsters, shrimp, and clams, specifically are not kosher. Fish, on the other hand, such as tuna, carp, and herring, are kosher, but only if they are prepared by a kosher fish monger with kosher cutting implements and machines. There's more. In most cases, scales must be present on the fish in order to be purchased by the consumer.
    * Fish and meat cannot be served together.
    * Milk and meat cannot be served together. Rabbinic law includes poultry in this prohibition, however fish is excluded. This gives rise to the popular, and kosher, bagel, lox, and cream cheese combination.
    * Processed food must be prepared in the presence of a rabbi.
    * Poultry and meat must be slaughtered under strict guidelines called "shechita." This means the animals are slaughtered without pain. Only those who are trained and qualified are allowed to slaughter kosher animals. Once the animal is no longer alive, another team of experts will examine the animal to be sure the animal is without illness, abnormalities or anything else that can be considered unsanitary. The lungs in particular must be pure. In addition, all blood, nerves, and most fat must be removed.
    * Kosher kitchens must maintain separate sets of utensils, pots, pans, dishes, and anything else that comes in contact with food. In addition, dishes and utensils in a kosher kitchen can't be washed together. If a kitchen has two sinks, it is an ideal setup for a kosher family. If not, separate wash buckets are often used. Dishes and utensils must be dried using separate racks or dishtowels as well.

There are many other rules to be followed for anything to be considered kosher food. To make identification easier on the consumer, kosher food is often identified as such by its kashrut certification on the food's package. Kashrut certification is generally indicated by an identifiable symbol that includes the letter K, or by the word pareve, which means the food is neither dairy nor meat, but rather neutral.

http://www.wisegeek.com/what-is-kosher-food.htm