Thai cookery - been there done that? Why not try Lao? Different enough from Thai to feel like a real adventure.
Great Lao guys teaching you to cook Lao food! $25 for the day, go to the market in the morning, cook all day then eat what you've prepared (washed down with a Beer - Lao of course!)
I thought it was one of the best value things we did in Laos. We cooked chicken laap (salad), coconut curry and jeow (chilli jam-paste-type thing) which required 50 chillis for a 2-person serving!
And can absolutely agree with the tip about the Tamarind Cafe. We ate the 'beer snacks' there and came back for more pretty quickly! Carolyn was fantastic and really helped with finding a cookery course. They do pretty advanced stuff at their school (and we are amateurs!) so she recommended Three Elephants.
It's advertised all over the place - you can't miss it. If you do, enquire in the Three Elephants Cafe or Tamarind cafe. Have some beer snacks while you're there!