Carne asada is a Mexican style of cooking, literally meaning "grilled meat." Most recognized with the meats Ranchera (Chuck Steak), it is one of the most popular staples to Mexican food. It can be found in tacos, tortas and burritos. Mexicans traditionally hold barbecues with carne asada as the main dish.
In Mexico and the American Southwest you will find that Carne Asada is the Mexican equivalent of Barbecue. It is meant in the party sense of the word. Traditionally a large fire pit is used to prepare this party but you can use whatever you have. Since everything is prepared over direct heat you don’t need a lid or a fancy grill. The cut of beef you use doesn’t need to be fancy either.
Carne asada can be traditionally prepared using lemon juice, garlic, and green or white onions. The beef is marinated in these ingredients and then placed on the grill.
Carne asada can also be marinated with beer and orange juice and instead of lemon juice, key lime juice.

According to wikipedia
Carne according to Troy
I grew up les than 20 miles from the mexico boarder Carne Asada is more than food its a life style. here's my recipe.
start with 2-3 pounds of cleaned top sirloin cut 1/4 inch thick(place in a bowl)
juice 2 lemons
juice 4 key limes
juice 2 navel oranges
1 tlb spoon of garlic
1 tlb spoon of each black peper ,white peper , oregeno,onion powder ,
and 1/2 tlb spoon cayane peper
slice up roughly 1 yellow onion
halve 2 jalepeno and 2 serano chiles
halve 1 package button mushrooms
rough chop 1 bunch of cliantro (steams are and leaves)
1 can cheap beer (bud )
1 cup soy sauce(yep it realy helps)
1/4 cup lee kum kee chile paste ( or any chile sauce i recomend this one its my favorite .)
now the important part is to leave it alone for 2 days . now thats it's ready fire up the grill grab some tortillias and some gaucomole and enjoy.