I've been eating this for years and taking it for granted for just as long. Eight years I went to a church with a large Polynesian community and all church events and pot lucks included large pans of rice, meatballs, pani popo, and of course sapasui. It wasn't until I moved that I realize I probably needed to learn to make it myself.
So I searched through the internet and came across what looked like a great recipe written by a guy who grew up eating this regularly. And because I think the blog name 1PlayerDad is clever I'm just going to link back to it, it's worth reading.
A few changes that I made though. I slow cooked the chicken thighs beforehand and shredded the meat and I added some cabbage, carrots, and green onions.