This is a delicious and simple dish that is fantastic with tortillas or, if you are being decadent, even added to a sharing plate of nachos. Beef flank is a fairly inexpensive cut of meat with a good amount of fat to keep it moist. It needs long, slow cooking to make it tender. You could use skirt steak if you can’t get flank.
Some crunchy salad goes very well here, no matter how you choose to serve it.