Au jus -- pronounced "oh-ZHOO" -- traditionally refers to a dish of roasted meat that is served with its own juices. In its simplest form, jus describes the pan drippings from the roasted meat. In practice, the jus is enhanced by deglazing the pan with stock and then simmering the liquid with mirepoix before straining and serving it. Au jus is generally -- but not always -- unthickened, which is what distinguishes it from a pan gravy.
Recipes for Au Jus
Methods vary for creating au jus for such dishes as roast rib of beef -- sometimes called prime rib. Poultry, lamb, and veal can also be served au jus. A thickened version of jus called "jus lié" -- or "fond lié -- is prepared by adding cornstarch or arrowroot to brown stock and then simmering.
Au Jus Debate
Au Jus is a French culinary term that literally means "with juice," according to Wikipedia, or "with the juice," according to Culinary Lore, but there is some debate in culinary circles about the exact translation of this delectable meat juice. If you look up the term "au jus" using online French-to-English translators, you'll find definitions as diverse as "with juice," "the juice," "in the juice" and just "juice." But, most sources agree that you want to avoid redundancy when using the term.
Culinary Lore, for example, notes that prime rib au jus means prime rib with the juice. Saying prime rib with au jus or prime rib with au jus sauce is redundant. Culinary Lore adds that another misuse of the term is French dip with au jus. "We can already see that 'with au jus' is redundant, but, as well, a 'French dip' without jus would be nothing more than a dry piece of meat inside bread or a roll." It's important to note that when you order a French dip, you are asking for a roast beef sandwich with a side of (its own) juice.
Importance of Deglazing
Deglazing is adding liquid such as stock or wine to a pan to loosen and dissolve food particles that are stuck to the bottom. The flavorful mixture produced by deglazing can then be used to make a sauce -- or jus. "The resultant jus may be seasoned, slightly reduced and strained," notes Culinary Lore.
You can achieve this loosening with water, but, of course, you wouldn't do so, because water doesn't have any flavor. Instead, you'd use wine or stock. Some recipes have you use thickening agents -- like flour -- to create a roux or paste before scraping the delicious caramelized drippings from the bottom of the pan. You then thin out the resulting liquid, creating the jus to add to your prime rib, French dip sandwiches or other dishes.