What kind of Steak in a Burrito?

One of my all-time favorite things on this planet is a steak burrito with white cheese sauce on top. We often frequent the Mexican chain called El Rancho. Anyway, I always get their Steak Burrito and of course, a Margarita.

I want to make these Burritos at home!

Here's what I think is in them:

1. Steak (no clue what kind they use!!)

2. Rice

3. Beans (re-fried)

4. Sauce (no idea)

I may be missing more ingredients but man, are they tasty.

What kind of steak does the typical Mexican restaurant use? It appears to be thin strips, never any fat or gristle. It's excellent! If I could buy this at the store and make my own Steak Burritos I may gain a few hundred pounds but I would certainly die happy. lol

Thanks for any advice or links to recipes!