This recipe makes perfectly creamy and thick soup but if you end up with runny & thin soup, the best way to thicken it is to use a cornstarch slurry. Simply mix a tablespoon of cornstarch with a tablespoon of cold water and turn it into a paste. Add it gradually to your simmering soup until it thickens to desired consistency. You can also thicken the soup by boiling it a bit further until the soup reduces down to desired thickness.