While it's not necessary to use a dough improver to make Banh Mi, it can help improve the texture and overall quality of the bread. A dough improver is a combination of ingredients that helps strengthen the gluten in the dough, resulting in a better rise, a more uniform crumb, and a longer shelf life. However, traditional Banh Mi recipes typically do not call for the use of a dough improver, as the bread relies on the natural fermentation process to create its unique texture and flavor. Ultimately, it is up to personal preference whether to use a dough improver or not, and the quality of the bread can be achieved without it.