Sobrebarriga is the Colombian name given to a specific cut of meat that comes from a cow. It refers to beef flank steak, a cut that comes from the underside of the cow near the back leg. Although the meat has a reputation for being tough and difficult to cook properly, there are certain techniques that are used in Colombian cuisine that can help to tenderize the meat. There are many recipes that use sobrebarriga, and the actual cut of meat is very popular all over South and Central America, as well as in Southeast Asia.
The toughness of the sobrebarriga can be attributed to its position on the cow. It is in an area that is worked constantly, developing the muscle mass of the animal and reducing the amount of fat. These factors combine to create meat that does not act like softer cuts that can be very tender after fast frying, instead producing meat that can potentially be stringy, tough and hard to chew.
The chewy and stringy nature of the sobrebarriga means it needs to be treated in a special way when cooking, and certain elements must be kept in mind when creating a recipe around it. Some ways to keep the meat tender are to introduce liquid into the muscle fibers or break apart the tough proteins between them. There are a few ways to do this, including through a marinade before cooking, a cooking method that involves liquid, mechanical tenderizing or a combination of all three.
In one classic preparation of sobrebarriga, the steak is placed in a marinade of garlic, onion, celery and tomatoes overnight before it is cooked. The next day, the meat is seared quickly in a pan and then braised in a mixture of vegetables, water and beer until it is done. This counteracts the toughness of the meat by adding moisture and breaking down some of the proteins with the marinade, then sealing in the juices with a fast sear, and finally dissolving any remaining tough proteins with heat and alcohol, while also adding flavor.
Another method of ensuring that the sobrebarriga is soft at the end of cooking is to mechanically tenderize the meat. This means hitting the steak with a tenderizing hammer or otherwise physically breaking tough strings within the meat so it relaxes and does not seize up under heat and become tough. This method is used when the steak is going to be quickly cooked, or is in small strips or cubes. An example of a recipe like this is a fajita.