There are a few different ways that you can thicken liquid without using cornstarch. One way is to use a thickener like arrowroot or tapioca starch. These thickeners will help to add thickness to the liquid without making it taste starchy. Another option is to use xanthan gum. This ingredient will also help to thicken the liquid while adding very little flavor. If you are looking for a vegan-friendly option, you can use guar gum, which comes from beans. Whichever thickener you choose, make sure to follow the directions on the package so that you don’t add too much and make the liquid become too thick.