Takes three days. Did some more sightseeing.
Don't know what it is - but Bangkok has plenty of them!
Not very popular.
Was walking on a busy street, noticed locals going through a gate, followed them to a little market, locals were not buying anything and were disappearing through a hole in a fence, followed them - a diner! Notice little sections at the perimeter - these are all different stalls preparing food. The cheapest in town.