I followed the recipe exactly except for the ground beef. I have a box of frozen angus burger patties in my freezer and opted to use those in lieu of the ground beef. Simply thaw them out in your refrigerator then crumble them into a pan--perfection! My only complaint was that the filling was a bit greasy from the hamburger. If you don't like the extra grease, cook your hamburger meat in a separate pan, drain the grease, then incorporate it into the onion & garlic mixture.
My roommate liked it so much that she made it again with her family the next day. It's a really fun twist on mexican-style cuisine.