Visiting a cooking school is a great holiday activity to partake in while in Indonesia. Indonesian cuisine is one of the most underrated cuisines I feel. It is really worth exploring the vast array of dishes and ingredients unique to their culture. There are really some amazing flavours.
There are several dotted around Bali but the most reputable schools are located in Ubud, which is a mountain village, around one hour drive from the airport which is worth visiting.
Updates
Not so sure about this. Attended a class at Casa Luna in Ubud, and found the whole experience a little removed from what I would have liked, specifically something that is hands on and not a demonstration.
Is this your business?