We had two kai soy Lao to try, the first, Mark's recommendation, was located across from Wat Vatsensoukharam. The second, the EatingAsia recommendation, was served by Mrs. Sum in the Luang Prabang morning market.
Wat Vatsensoukharam kao soy
Finally, the much touted bowl of fresh herbs and vegetables were nowhere to be seen, and instead the kao soy was served with a little bit of lettuce and herbs already in the bowl. This gave me the feeling that the proprietress, as much or as little as she may have vaguely resembled Aung San Suu Kyi, was resting on her laurels now that she had a steady tourist clientele. Overall, a great bowl of kao soy but I wasn't as fully convinced as Steven, perhaps because I don't have a bone for Aung San Suu Kyi. -Lina