Mix Some of the Soup to Thicken Quickly
Clear soups are delicious, but if you want a thicker and more filling soup, you don’t need to add cornstarch or flour, you can mix part of the soup to thicken the rest. An immersion blender works best. If you don’t have one, you can also use a potato shredder or stand-up blender.
As Christina Gallary, writing on Kitchn, points out that this method will not thicken the soup without changing the flavor, like the slurry opposite to the gravy that is added at the end of cooking. She also warns that if there are bones in your soup, you must remove them before mixing. For more tips on this method, see the full post at the link below.
The Easiest Way to Thicken Soup | Kitchen