A famous question in Hilchos borer is what to do when a fly falls into your soup. Assuming you want to continue eating the soup, how should the fly be removed? The Be’er Hetev 319:2 brings a machlokes whether something that is floating in a liqid is considered mixed together. If it is, the unwanted object is subject to the laws of borer, and may only be removed prior to eating, good from bad, and only by hand. The Mishne Berura in 319:61 rules that this is indeed a mixture, and suggests to remove the fly with a spoon along with some of the liquid. To remove the fly without any liquid is taking the bad from the good, and is forbidden. The same would apply to any unwanted object inside a drink or soup.

Rabbi Tzvi Aryeh Hyman, Mir Yeshiva, Israel.