Tapioca flour is the traditional and essential ingredient for making Brazilian cheese balls. However, if you cannot find it or prefer to use an alternative flour, you can try using potato starch, or arrowroot flour as a replacement. These flours are similar to tapioca flour in terms of texture and can be used in a 1:1 ratio substitution. However, keep in mind that each flour will have a slightly different taste and texture, which WILL affect the final outcome of your vegan pao de queijo recipe.