Thickening liquids into sauces. How to add oomph to your dishes.

September 26, 2023


A French cooking method called “monter au beurre” is a good way to thicken a sauce for this Braised Whole Leg of Chicken.
A French cooking method called “monter au beurre” thickens the sauce for Braised Whole Leg of Chicken. Photo by Bill St. John, for UCHealth.

Soup isn’t the same as sauce. But often, it’d be nice to boil it down to that.

Wet cooking (sometimes called “braising”), done either in two popular modern cooking appliances — the Instant Pot and the slow cooker such as Crock-Pot — or in more traditional ways in a Dutch oven atop the stove or in the oven, tends to render sauces that, as sauces, are thin and wan. Such may make for delicious soups, but aren’t, as a rule, a toothsome nap for their meat and vegetables.

Braising liquids almost always could use some oomph before hitting the serving plate. To the rescue comes a raft of ways to thicken those liquids into sauces on all fours.

Powders and flours

Cornstarch, arrowroot, common wheat flour, and the flours or powders made from potato, tapioca, chickpea — to name but a few — long have been used to thicken cooking liquids. (Gelatins and gums also can play a similar role.) Generally, it’s best to make a slurry of any of these before adding to and then heating them in the liquid that’s being worked.

Reversing the order of preparation, some cooking preparations make a roux or coat some ingredients in flour at the outset of the braise.

Some cooks aren’t attracted to starches, however, because they feel that each dilutes or even dulls the flavors and aromas that have been coaxed into the braise.

A turn on the use of flour as thickener is the French “beurre manié,” equal portions of butter and flour kneaded into a paste, then added to liquid and cooked.


Any liquid may be boiled or evaporated of its water, or “reduced.” Deglazing a skillet with a liquid such as wine or broth, in order to scrape up those tasty brown bits after an early step in certain recipes, is a form of reduction.

But even those soupy results from a slow cooker beef pot roast profitably may be reduced in a separate skillet or saucepan and, so, thickened into a sauce.

More great tips and recipes from Bill St. John.


I often simply drain in a sieve the cooking vegetables (likely onions, carrots, celery, and tomato) from a braise, and blend or purée them, adding them back into the liquid which, of course, has been saved in a saucepan, not discarded. They nicely thicken the liquid into a hearty sauce.


Saving the best for last, we have “monter au beurre,” a French term that means to add butter to a liquid in order to give it more body and increase its volume. What it doesn’t say outright is that it also exponentially magnifies its awesomeness, luxuriousness, and elegance.

Tomato paste and hot sauce helps you thicken a sauce for this Poulet au Vinaigre (Chicken in Vinegar), a specialty of Lyons, France.
Tomato paste and hot sauce help you thicken a sauce for this Poulet au Vinaigre (Chicken in Vinegar), a specialty of Lyons, France. Photo by Bill St. John, for UCHealth.

The cook gently whisks small amounts (what those in the U.K. so comfortably call “knobs”) of butter into a quite warm but not simmering liquid — which itself, and I would counsel so, has been reduced — until the butter melts into the liquid, slightly emulsifying it, and taking it to another order of deliciousness.

Monter au beurre is the finish to the first of the recipes here, Braised Whole Leg of Chicken.

The second recipe, a second chicken treatment called Poulet au Vinaigre, is a specialty of Lyons, France and the chef who developed this recipe, the renowned Jacques Pépin. Its sauce is thickened by a deglazing and a couple of quick reductions.

Braised Whole Leg Chicken

The classic, age-old chicken braise is in white wine or chicken stock, unless it’s the “coq au vin” variation, then in red wine. Why not split the difference and braise it in the increasingly popular, now-year-‘round rosé? Of course. Makes 6 servings.


6 whole leg chicken legs (thighs and drumsticks unseparated)

Kosher salt and freshly ground black pepper

Bread flour for dredging

4 tablespoons vegetable oil or ghee

2 large shallots, peeled and chopped

1 large carrot, peeled and diced

2 celery stalks, diced

1 cup rosé wine (or a mix of red and white wines, or a mix of tart cherry juice and apple juice)

2 cloves garlic, peeled and minced

2 tablespoons herbes de Provence

3 cups chicken broth

3 tablespoons unsalted butter, cold and in 3 pieces

2 tablespoons flat-leaf parsley leaves, chopped

Lemon rind to taste, zested or in very thin strips


Sprinkle salt and pepper on both sides of the chicken pieces and place in a closed container or plastic bag and refrigerate a few hours or overnight. When ready to cook, heat the oven to 450 degrees and place a cup (or more) of flour in a large bowl; dredge each chicken piece, shaking off excess flour and place aside.

In a large oven-proof skillet over a medium-high burner, heat the oil or ghee and brown the chicken legs on both sides until nicely colored; if necessary for space, brown in batches. Remove the chicken after it is browned, keeping back only 2 tablespoons of fat. In it, brown the shallot, carrot, and celery for 10 minutes, stirring. Add the garlic, more salt and pepper if desired, and the herbs; stir well, 2-3 more minutes.

Remove the vegetables to the side and deglaze the skillet with the wine (or juices) and evaporate most of it, scraping up any browned bits and leaving only about 1/4 cup liquid in the pan. In the skillet, arrange the vegetables so that they are in a flat layer and form a bed for the chicken pieces.

Place the chicken legs on the vegetables, skin side up, then add enough broth to the deglazing juices to come up about halfway on the chicken, not enough to cover it. Bring all this to a simmer on top of the stove, then place the skillet in the oven, uncovered. Wait 10 minutes, then turn down the oven heat to 325 degrees and cook the chicken for 35-40 minutes or until it is very tender and the skin has nicely browned, even crisped. Remove the skillet and take out the chicken legs, placing them aside in a warm spot.

Into a saucepan, strain the liquid from the skillet of its solid matter, pressing down on the solids if feasible, and skim the liquid of fat if significant. Reduce the sauce a bit if it is wan and thin.

Warm up the sauce and then remove it from the heat. Gently whisk in the cold pieces of butter, one at a time, until each piece melts and is incorporated into the sauce before adding the next. When the sauce is finished, serve the chicken napped with it and sprinkled with the parsley and lemon zest.

Poulet au Vinaigre (Chicken in Vinegar)

Adapted by Bill St. John from Jacques Pépin, “A French Chef Cooks at Home” (Fireside Books, 1975) and from his video of the recipe of the same name.


2 large or 3 small-to-medium chicken thighs, skin-on and bone-in

Kosher or sea salt and freshly ground black pepper

3 garlic cloves, peeled, smashed well and chopped fine

3 tablespoons red wine vinegar

3 tablespoons water

1 tablespoon tomato paste

Dash of Tabasco or other hot red pepper sauce


Lay the chicken thighs skin side down and cut along both sides of the bone on each, being careful not to cut all the way through to the skin, simply loosening the bone against the meat.

Salt and pepper both sides of the thighs. Using a dark, cold, non-stick skillet with a tight-fitting lid, lay the chicken thighs in the skillet, adjust the heat to medium-high and begin searing the chicken thighs. (Do not add any oil or butter to the skillet and do not flip over the thighs during any part of their cooking.)

When the thighs release enough fat from their skins and begin to brown well, about 5 minutes, cover the skillet and lower the heat to low, allowing the covered skillet to steam-cook the thighs, 20-25 minutes.

Remove the thighs with tongs and set them aside on a warmed plate. (The skin side should be nicely browned.) Raise the heat on the skillet to medium-high and add the garlic, stirring and cooking for 30 seconds. (Do not burn the garlic or the sauce will be embittered.)

Add the vinegar and water, stirring to loosen all the accumulated brown bits and to vaporize the acidity of the vinegar, 1-2 minutes. Add the tomato paste and hot sauce, stirring them in and thickening the sauce, 1 minute.

Serve with buttered new potatoes sprinkled with chopped fresh flat-leaf parsley.

 Reach Bill St. John at [email protected]

About the author

For more than 40 years, Bill St. John’s specialties have been as varied as they are cultured. He writes and teaches about restaurants, wine, food & wine, the history of the cuisines of several countries (France, Italy, Spain, Belgium, and the USA), about religion and its nexus with food, culture, history, or philosophy, and on books, travel, food writing, op-ed, and language.

Bill has lent (and lends) his subject matter expertise to such outlets as The Rocky Mountain News, The Denver Post, The Chicago Tribune, 5280 Magazine, and for various entities such as food markets, wine shops, schools & hospitals, and, for its brief life, Microsoft’s In 2001 he was nominated for a James Beard Award in Journalism for his 12 years of writing for Wine & Spirits Magazine.

Bill's experience also includes teaching at Regis University and the University of Chicago and in classrooms of his own devising; working as on-air talent with Denver's KCNC-TV, where he scripted and presented a travel & lifestyle program called "Wine at 45"; a one-week stint as a Trappist monk; and offering his shoulder as a headrest for Julia Child for 20 minutes.

Bill has also visited 54 countries, 42 of the United States, and all 10 Canadian provinces.