This stall is about two streets from Khowsan Road and it's the place to try the best Tom Yum Goong in Bangkok so it's handy for the backpackers. If you are staying in the City combine it with a trip to the Grand Palace - it's not far from there.
Get a tuktuk to Khowsan Road and navigate from there. You will need to use your detective skills to find it as there is no name but it is halfway up the street on the left with Samsen behind you and it sits at the base of a multi story carpark.
There is only one chef who makes the soup and he is in this photo - he always wears a baseball cap - also you may recognise the pan. Hopefully I have given enough clues for you to find the correct stall.
It is quite remarkable what he produces in one old battered little pan, feeding hundreds each day. They also make great, bouncy aerated fishcakes too so give them a try if you can.