Why It Works
- Homemade brown duck stock produces a sauce with rich, roasted-meat flavor while reduced red wine adds subtle sweetness and acidity.
- Powdered gelatin gives the sauce added body without the need for purchasing and simmering extra collagen-rich bones.
- An optional spoonful of shio koji gives the jus added savory depth and strengthens the background sweetness of the wine.
Making a glossy, spoon-coating, restaurant-worthy jus at home isn't hard. It just requires time, patience, and some high-quality, homemade stock.
For our Big Duck Project, we wanted to pull out all the stops for a duck jus worthy of the occasion. To make this sauce, we start by reducing our brown duck stock and red wine separately on the stovetop, until the wine has cooked off most of its alcohol and concentrated to a syrup. The reduced wine is then added to the simmering stock, along with some bloomed gelatin that gives the jus body without the need for purchasing a bunch of collagen-rich bones to cook down with the stock.
As the stock simmers and reduces, fat and impurities are skimmed off, to produce a smooth, silky sauce. For the best results, we recommend straining the jus into a smaller saucepan as it cooks down, to get rid of any sediment particles from the stock. This optional step may seem fastidious, but it leads to a shiny sauce, free of any grit.
Once the jus has reduced to the perfect spoon-coating consistency, it's ready to be seasoned. Season a sauce that is still reducing is always a risk, since it's possible the salt will grow overly concentrated as the water content evaporates. Holding off on seasoning until the very end therefore ensures that we aren't left with an inedibly salty sauce.
The duck jus can be simply seasoned with salt, or you can stir in a spoonful of blended-smooth shio koji, which lends the sauce not just salt but also savory depth as well as a little background sweetness. Either way, you will be left with a rich, meaty jus, perfect for spooning over roast duck and vegetables alike.
Pour 1 cup (240ml) of duck stock in small bowl or liquid measuring cup and evenly sprinkle gelatin over surface of stock. Set aside. Transfer remaining stock to 3-quart saucier. Pour wine into separate medium-size saucepan.
Set saucepans of wine and stock on stovetop and bring each to a boil over high heat, then reduce heat to maintain both at a rapid simmer. Cook, uncovered, until wine is reduced to syrupy consistency that measures about 1/2 cup (120ml) in volume, about 40 minutes.
Add reduced wine and gelatin-enriched stock to saucier of simmering stock. Continue to cook, adjusting heat to maintain simmer and occasionally skimming fat and scum from surface of liquid with a ladle, until liquid has darkened in color, thickened to a sauce-like consistency, and reduced to about 1 1/2 cups (355ml), about 50 minutes. For glossy jus with few impurities in it, midway through reducing, strain jus through a fine-mesh strainer into a smaller saucepan and continue to reduce until liquid has achieved proper consistency.
Using a spoon, test the consistency of sauce; jus should coat the back of a spoon when dipped in it, and when you drag a finger over the spoon, it should leave a clear path.
Season jus with shio koji (if using), adding 1 tablespoon (15ml) at a time and stirring to incorporate into the sauce, until desired flavor is reached. Season with salt (if using shio koji, additional salt may not be needed). Jus can be used right away or cooled and refrigerated in airtight container until ready to use.
Shio koji adds savory depth, salinity, and subtle sweetness to the jus, but the success of the sauce doesn't hinge on its inclusion. If you don't have any shio koji on hand, you can simply omit it, or substitute an equal volume amount of kecap manis. The flavor of Indonesian sweet soy sauce is different from that of shio koji but hits on many of the same notes—salty, sweet, slightly funky, and umami.
Make-Ahead and Storage
Duck jus can be refrigerated in an airtight container for up to 1 month, or frozen for up to 6 months. To reheat, warm gently in a saucepan over low heat or in a microwave-safe container in the microwave.