Tanin-don or tanin-donburi is a dish in which beef or pork that is boiled with onions in a stock mixed with soy sauce, mirin and sugar, stiffened with eggs, and then placed on donburi meshi (a bowl of boiled rice). Tanin-don is a kind of Donburimono.
Tanin-don is basically made using the recipe same as Oyako-don. Oyako-don is made using chicken and eggs, whereas tanin-don is made using meat except for chicken (beef or pork), i.e., using meat of a stranger for an egg; hence tanin-don is named after this recipe. There is also tanin-udon in which the ingredients of tanin-don are placed on kake-udon (Japanese wheat noodle with broth).
Difference in names
Mainly in the Kansai region, donburimono using beef is called "tanin-don." In areas other than the Kansai region, "tanin-don" usually refers to the donburimono using pork. In the Kanto region, donburimono using beef is called "kaika-don." The reason for this came from the thought that beef was a symbol of westernization of Japan like sukiyaki, and the call "tanin (stragner)" sounded humble. However, some restaurants served kaika-don using pork. A possible reason for this is that kaika-don was interpreted as another name for tanin-don.
Primarily, the Kansai region is the birthplace of the name "tanin-don." In this name, a spirit of the people in the Kansai region appears saying "a stranger is a stranger." Donburi with beef meant "tanin-don" until Gyu-don (donburimono with cooked beef on cooked rice) chains such as Yoshinoya penetrated into the Kansai region. Many noodle shops and restaurants still have menus without Gyu-don but have with Tanin-don.
Restaurants in the country side often serve "tanin-don" under tha name of "oyako-don" in which pork used in stir-fried dishes is used instead of chicken to save preparing time and effort.