Ox tongue is the tongue of a cow and can be roasted, braised, boiled or pickled. In Japanese cuisine, it is served in a grilled dish called "gyūtan," which literally translates to "beef tongue." They can be found, pre-sliced, in the frozen section at most Korean or Japanese foodstores and are extremely easy to prepare.
I bought a packet from a Korean grocery store, in the "BBQ foods" frozen section, and thawed the meat for a couple of hours (you can even cook them from frozen, however it is harder to separate the slices). To cook, I simply placed each slice straight onto a pre-heated, non-stick frying pan. They only took about 2 minutes to curl up and brown, releasing sweet, natural juices and a wonderful barbecued aroma. I simply served with a generous squeeze of fresh lemon juice and cracked white pepper.
Ox Tongue with Lemon Juice - so flavoursome with a slight resistance to the bite