Nothing to stick your tongue out at
Gyūtan, or beef tongue, is a common meat in Japanese Yakiniku restaurants. The meat is particularly fatty, with roughly 75% of its calories derived from fat. While many people may consider tongue meat to be difficult to stomach, it is actually quite commonly eaten around the world. In Europe, tongue dishes are common in Belgium, Poland, Germany, Austria, Romania, Spain, Portugal, and Turkey, in Latin America, in Mexico and Brazil, and in Asia, Korea, Indonesia and the Philippines.
In Japan, the most famous place for beef tongue is in Sendai. There, gyūtan was made into a common food by the owner of a yakiniku restaurant in 1948, during the U.S. postwar occupation. The occupied forces consumed far more beef than Japanese did until then, but they did not eat tongue and other parts of the cow that were considered unpalatable. Since the surplus of beef parts made tongue very inexpensive, an entrepreneurial chef made gyūtan his specialty.
Unlike the tan-shio served now at most yakiniku restaurants, Sendai-style gyūtan is thicker, juicier, and flavored. Rather than just one of a variety of cuts eaten in a meal, it is generally served as a main course. It is hearty food, extremely popular among businessmen and students.
Despite its high fat content, gyūtan is extremely tasty and I highly recommend it!