Q. After meals on Shabbos, is it okay to use some liquid dish detergent?

A. Horav Shlomo Miller Shlit”a ruled that when soaking dishes in cold water is permitted on Shabbos (see prior question) it is also permitted to add liquid soap to the water when needed now to avoid foul odors or attracting insects.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a