It's a three cornered pastry type food, filled with something, usually a sweet filling eaten for the holiday Purim, which happens around this time of year. (This year it's mid march).

There are a bunch of Jewish holidays with the same theme-they tried to kill us, we survived, let's eat. This is another one of those holidays. This time the story involves a bad guy named Hamen. Hence, Hamentaschen.

They're good stuff. One of my favorite Jew Foods.