We also learned a Saigon cooking lesson in Ho Chi Minh City and saw many Vietnamese cuisine practices. This trip benefited a lot and gained a lot.
If you want to take a half-day cooking course in Ho Chi Minh City, you can contact the cooking school directly by yourself. There are many schools in Ho Chi Minh City, which have different characteristics but not too big differences, so you can choose freely. Travel agencies can also be used everywhere. Of course, travel agencies are more expensive, about $50, and will be responsible for the hotel to the culinary school pick-up, booking is more convenient than you find your own school.
It's also a pleasure to learn how to cook good food, especially to make something you like by hand.
Follow the local people to buy ingredients, and then learn to cook local dishes with the local people.