There are a number of Bahn Mi recipes out there. The one I recommend is based on the one from "Real Vietnamese Cooking" p.28 by Tracy Lister and Andreas Pohl.
The recipe can be summed up as: AP flour 100% – Rice Flour 16% – Salt 3% – white granulated Sugar 8% – Dry Yeast 7% – lukewarm Water 91%
I prefer a little less salt in my breads and so normally knock the salt down to 1.5% - 2%
Edit ( Oops Didn't see Helen up further in the thread, my bad.) Helen's Recipes on Youtube does a good job of describing the baking process.
Addendum: Alternative recipe translated, from video of a commercial bakery in action, on Michael Duong's youtube channel.
1/2 an egg, 600g water, 1kg bread flour, 100g salt, 60g yeast, 60g Additives (Improver?) – cut 120g per portion. Proof in humidity cabinet at 35-40°C. Bake at 210°C for 12 minutes. [noted: no rice flour in this one ]