Saigon street food tours is a must try when you travel to . We called street food that is not mention to cheap and unsafe foods, the people from 3 regions of Vietnam immigrated here and they brought their typical foods to Saigon, not only food, it hold culture of each region when we try it.
There many options for you to choose.
Going by scooters around Saigon or walk to a selected markets that will be in your decision.