Reducing a sauce or any other liquid seems like such a matter-of-fact, unambiguous step in a recipe. But I admit that I often feel a knot of anxiety grow larger the longer I hover over the pan of simmering, steaming liquid. Does it look like a cup now? Is that about half? Should I keep going?
Today, let's relieve some anxieties. Here are some things you should know about reducing sauces, soups, and other liquids, and three ways to tell when they are ready.
Why Reduce Liquids When Cooking?
When a recipe asks you to reduce a sauce or other liquid the primary reason is usually to concentrate the flavors. As water evaporates from a sauce or soup, the flavors of the remaining ingredients concentrate and intensify. The longer the liquid simmers, the more intense and concentrated the sauce or soup's flavor will become.
Reducing liquids can also change their texture, making sauces thicker and silkier, and giving soups more body. Again, the longer you reduce a sauce, the more luxurious and thick it tends to be.
The good news is that you don't usually need to be 100 percent exact when reducing a sauce — it's fine to guesstimate. The difference in a sauce that was reduced to one cup and a sauce that was reduced to one cup plus a few tablespoons will be very slight. Also, if you accidentally reduce the sauce more than you like, you can usually just add a little extra water or broth to dilute it again.
The only time you need to pay closer attention is if the exact amount of the reduction is crucial for the recipe to work properly, like if it's an ingredient going into a pastry or other baked good. These recipes may rely more heavily on exact amounts to ensure that the pastry cooks properly and tastes correctly at the end.
1. Guesstimate by tilting the pan.
Tilt the pan once when you first begin reducing to get a starting point, then tilt the pan again every so often as it reduces down. You should be able to use this to roughly gauge both how quickly the sauce is reducing and how far it has reduced.
I find this method is best when reducing small amounts of liquids, like for a sauce or a syrup — anything under a cup or two of liquid. With amounts this small, it's usually pretty easy to estimate how far the liquids have reduced just by looking.
2. Use a jury stick.
Make a jury stick by wrapping a rubber band around a chopstick or skewer and inserting it in the liquid when you first start reducing. Roll the rubber band down the chopstick until it touches the surface of the liquid — this is your starting point. As the liquid reduces, occasionally insert this jury stick into the liquid and use it to tell how far the liquid has reduced.
I prefer using this method when I'm reducing a larger amount of liquid, like a soup, where tilting the pan might either be difficult or might not give me a very accurate reading. If you want to get really fancy, you can mark your jury stick with 1-cup increments so you know exactly how much liquid has evaporated, cup by cup. Do this by filling your pan with cups of water before cooking and marking the jury stick with each one-cup addition.
In a pinch, I've also gone by the rings left on the side of the pan by the evaporating liquid. I find it a little harder to estimate this way, but it works in a pinch if I forgot to make a jury stick when I first started reducing.
3. Pour into a measuring cup.
If you want to be very accurate, it's best to pour your sauce into a measuring cup once you think you're close to your mark. Remember to use heat-proof measuring cups with your steaming-hot liquid to avoid cracking or shattering the measuring cup.
This is certainly the most accurate method, but in my opinion, it's also the most fussy. Not only do you have to deal with carefully pouring hot liquids into a measuring cup, but if you haven't reduced enough, you need to pour everything back in the pan, bring it back up to a simmer, and keep cooking. I use this method only when reducing a specific amount seems crucial to the recipe.