How to Make It
In a medium bowl, using a rubber spatula, stir the yogurt with the sour cream until well combined. Line a fine-mesh strainer or colander with 3 layers of cheesecloth, leaving a 4-inch overhang on 2 sides, and set the strainer over another medium bowl. Scrape the yogurt mixture into the cheesecloth. Twist the overhanging ends of cheesecloth together and tuck them under the ball of yogurt. Place a small bowl on top of the cheesecloth bundle and refrigerate overnight.
Unwrap the cheesecloth bundle and scrape the labneh into a bowl. Sprinkle with salt, stir with a rubber spatula and serve.