Hoisin sauce (also known as Chinese plum sauce) is a thick, pungent sauce commonly used in Chinese cuisine as a glaze for meat, an addition to stir fries, or as dipping sauce. It is darkly colored in appearance and sweet and salty in taste. Although regional variants exist, hoisin sauce usually includes soy, red chiles, and garlic. Vinegar and sugar are also commonly added. The word hoisin is from the Chinese word for seafood (海鮮, Cantonese: hoi2 sin1 Mandarin: hǎixiān).
Peking-style hoisin sauce ingredients include starches such as sweet potato, wheat or rice, and water, sugar, soybeans, sesame seeds, white distilled vinegar, salt, garlic, red chili peppers, and sometimes preservatives or coloring agents. Traditionally, hoisin sauce is made using toasted mashed soy beans. Despite the literal meaning, hoisin sauce does not contain seafood, nor is it typically used with it. Neither does it contain plums, even though it is frequently misidentified as plum sauce.
In Vietnamese, hoisin sauce is called "tương đen". It is a popular condiment for phở, a Vietnamese noodle soup. However, as a condiment, it is primarily used in Southern style phở. Hoisin sauce is not served alongside Northern style phở. The sauce can be directly added into a bowl of phở at the table, or can be used as a side dip for the meat of phở dishes. In phở, hoisin is typically accompanied by Sriracha sauce or "tương đỏ". The hoisin sauce is also used to make dipping sauce for Vietnamese spring rolls and other dishes similar to spring/summer rolls. In cooking, it can be used for glazing broiled chicken.