France is considered a culinary mecca, largely due to the complicated methods and sauces developed by its chefs through history. One of the more nuanced and historical compound French sauces is called sauce Robert, pronounced "roe-bear." This mustard-tinged brown sauce is often paired with meat and potatoes dishes to impart diverse flavors from white wine, vinegar, butter, Dijon, tomato paste and the core of many Western cuisines, mirepoix — a diced mixture of carrots, onion and celery.
According to the 1973 book Mastering the Art of French Cooking, in which chef Julia Child famously educated the larger Western world on the finer points of the country's culinary expertise, sauce Robert is a version of core French sauce called espagnole, which requires precision. It starts with a traditional brown sauce, or demi glace, which is common to many French dishes. This sauce often includes a mirepoix, butter, bacon, tomato paste, flour and beef stock. It also typically includes several herbs like thyme, bay leaf and parsley.
Merely combining all these ingredients into a small pot will not suffice. First, a roux is formed, which is a blend of clarified butter and flour. Into this base go meat stock and a little water, along with the mirepoix, some crisped bacon, and herbs. At the end, after forming into a gravy, some tomato paste is added, along with more stock, if needed.
While the sauce is being built in one pan, another pan holds a diced onion caramelizing in butter. Before the onions are browned white wine is added to the pan, and this continues to simmer until the alcohol content is cooked off. The demi glace and wine-soaked onions are then stirred together and cooked until the sauce Robert has a thick consistency. The last step is a dollop or two of Dijon mustard, along with more butter and salt and pepper to taste.
It is unclear to whom the "Robert" in sauce Robert refers. No one is quite certain how many hundreds of years it has been a French culinary staple, either; some have dated it to 600 years ago. It is undeniable, however, that sauce Robert has an established place as a fundamental component in French cooking, with its ingredients remaining unchanged for at least four centuries. It is still regularly found slathered over beef, pork and other meats as well as potatoes when served as a side dish.