2 Answers

Eastern European immigrants who arrived sometime around 1900 brought knishes to North America. Knish (????) is a Yiddish word that was derived from the Ukrainian "knysh" (Книш),meaning "a kind of bun." Effectively meaning Knish = Bun-ish. It is a baked or fried dumpling made of flaky dough with filling. The first knish bakery was founded in New York in 1910." Generally recognized as a food made popular in New York by immigrants in the early 1900's, the United States underwent a knish renaissance in the 2000's driven by knish specialty establishments such as the Knish Shop in Baltimore, Maryland,[6] Buffalo and Bergen in Washington, DC, or My Mother's Knish, in Westlake Village, California.
A knish consists of a filling covered with dough that is either baked, grilled, or deep fried. Knishes can be purchased from street vendors in urban areas with a large Jewish population, sometimes at a hot dog stand or from a butcher shop.
In the most East European traditional versions, the filling is made entirely of mashed potato, ground meat, sauerkraut, onions, kasha (buckwheat groats), or cheese. Other varieties of fillings include sweet potatoes, black beans, fruit, broccoli, tofu, or spinach.
Many cultures have variations of baked, grilled, or fried dough-covered snacks to which epicurean family the knish belongs including the Cornish pasty, the Scottish Bridie, the Jamaican patty, the Spanish and Latin American empanada, the Middle Eastern fatayer, the Portuguese rissole, the Italian calzone, the Indian samosa, the Polish pierogi, the Russian Pirozhki, and the Ukrainian Pyrizhky.
Knishes may be round, rectangular, or square. They may be entirely covered in dough or some of the filling may peek out of the top. Sizes range from those that can be eaten in a single bite hors d'oeuvre to sandwich-sized.

http://en.wikipedia.org/wiki/Knish

i love 'em...the round, not the square ones. Here's my favorite place n NY. Might go there tomorrow. http://www.yelp.com/biz/knish-nosh-forest-hills