Cerveza Preparada ("Prepared beer") is a Mexican term for a mixed beer drink involving juices and/or sauces. In English cerveza preparada would be considered a beer cocktail, or a variety of shandy. The drink dates back to the 1940s, when mixing beer with tomato juice and hot sauce or salsa became popular in Mexico.The basic recipe is tomato juice (or sometimes Clamato or V8) juice mixed with Mexican beer (Corona or Negra Modelo) and the juice of half a lime in an ice-cold, salt-rimmed pint glass. Add the beer by pouring it from high above the glass so the contents can mix properly.
Variations
Michelada
A Michelada is similar to a Bloody Mary but contains Mexican beer instead of vodka.
Chavela
Chavela is a Cerveza preparada that is popular in Mexican restaurants as both a drink and as an appetizer if served with a garnish. It is made with tomato, V8, or Clamato juice mixed with beer, and seasoned with Hot Sauce (i.e., Tabasco, Tapatio, Bufalo, etc.). It is served in an ice-cold
Source:
http://en.wikipedia.org/wiki/Chavela