This is the Burmalı Mescit, "burmak" is "to twist", which is what the decoration on the minaret does. The building is from 1550, built by Kadı (judge) of Egypt, Emin Nurettin Osman Efendi. I did not enter, it being closed, but it is described as being of the simplest kind, a square room with a flat wooden ceiling, so you don’t miss much. The porch is unique in that is has a pitched (not domed) roof, with Byzantine Corinthean capitals. I did not pay particular attention, having seen this elsewhere, but for Istanbul it seems to be special. I’ll correct this someday.
You will come across this mosque after having visited Şezade Mosque and heading for the Valens Aquaduct.