Which non-mainstream markets do you like?

New to Thailand. I love the vibe of Old Phuket but noticed that it's mostly the kind of food that appeals to western tastebuds. Delicious but not the healthiest selection. I wandered southeast and ended up in Kaset Market completely by accident. To my delight, one of the cooks made me a heaping plate of kale and egg. I ate it and the next day I had the best bowel movements of my life! Haha. So...it wasn't 100% healthy because it was stir fried, but hey at least I got my vegetables in. I discovered this market just by chance though. I'm curious what other non-tourist markets I may not know about.

Also...can I trust the sashimi at night markets?