Hello there. Running out of cornstarch in the middle of preparing dinner happens all the time, but you have several reliable pantry options to get your sauce nicely thickened without any trouble.
The most accessible alternative is standard all-purpose flour. Because flour has a lower starch concentration than cornstarch, you will want to double the amount. Use roughly two tablespoons of flour for every one tablespoon of cornstarch your recipe requires. To prevent lumps, whisk the flour into a small amount of cold water or liquid from your recipe until it forms a smooth slurry. Pour this mixture into your gently simmering sauce while whisking continuously. Be sure to let it simmer for an extra three to five minutes so the raw flour taste cooks out and the starches fully activate.
Another simple method is cold butter emulsification. Cut a couple of tablespoons of very cold butter into small pieces and whisk them into your warm sauce off the heat just before serving. As the cold butter melts into the liquid, it creates a subtle richness and thickens the body of the sauce while giving it a glossy appearance.
If you have a bit of extra time, you can also use simple reduction. Leave the pot uncovered over low to medium heat and allow the sauce to simmer. As steam escapes, water evaporates and the liquid will naturally thicken while concentrating the flavors.
Lastly, if you happen to have potato starch, tapioca starch, or arrowroot powder in your pantry, you can use any of those as a direct one-to-one substitute for cornstarch using the same cold liquid slurry technique.
I hope one of these solutions helps you finish your dinner smoothly tonight. Best of luck with your meal.
