I haven't taken the cooking class at May Kaidee's vegetarian restaurtant, but I've eaten there. Recommended.

Kinda hard to find off Khao San road in the traveler ghetto. (N13 45.509 E100 29.963 for you GPS fans.)

Go to the east end of KSR. Cross the street. Turn left. Go to the first alley and you'll see a sign for "Number One Vegetarian Restaurant." Go down the alley and turn left and you'll see a sign for May's.

Try the larb, which I found quite good and, unusually, made with noodles. (Free, unsecured wifi in the area. Use SSID "Netgear" at your own risk.)