Empanadas are very popular as a street food in South America. Essentially, it is a crescent-shaped pastry with a filling, which may vary greatly by region or preference. Empanadas can be fried or baked, and may use a variety of fillings from meat or seafood to fruit or cheese. While this recipe uses the filling most popular in Buenos Aires, you can fill an empanada with virtually anything you please, so experiment!
Tip: A recipe for empanada dough is given here, but they can be found in the frozen pastry section of many specialty or Hispanic groceries. If you are in a rush or just feeling lazy, frozen puff pastry can serve as an adequate substitute.
Note: To the reviewer who said the flavor did not seem authentic, you probably haven't had meat empanadas from Argentina then! I am Argentine, and the ground beef empanadas you find there *always* have cumin. Other cultures may have different fillings.