It was quite an interesting and fun experience (was first time for me):
The FA comes down the aisle with the food cart where the food is in big open containers and they ask you what you would like to have.
So it is easy to say "more of this / none of that" etc.
I do not know if they do refills, but I personally did not feel the need as the portions prepared out by the FAs were quite generous
I also found the food far tastier than the one served on the long haul to / from BKK.