I've seen my share of burgers by the bag. The wonderful Telway chain of slider joints in Detroit will send you packing with a pack of pint-sized patties for a few bucks. White Castle, the inventor of the slider, is famous for selling their burgers by the sack- (or case-)ful. Even the local McDonald's franchise in Cambridge's Central Square used to have a 12 burgers-for-$10 sack deal after 10pm, back in my college days (I suspect they just needed to move old product).
Soft sliders by the sack totally works. The buns soften and flavors meld in their beef- and onion-pumped gas chamber. If anything, sliders get better by some judiciously applied bagging.
But a bánh mì, with its crisp, moist vegetable filling and delicate-crusted bread? There's a reason that bánh mì should be eaten as soon as possible after assembly.
The folks behind the sandwich counter at the Tien Hung Oriental Foods market in Orlando's ViMi district (one of the finest Vietnamese food scenes in the country) seem to know this and have come up with an ingenious workaround: rather than selling the 100% assembled sandwiches, they'll give 'em to you as DIY kit.
In the bag are 6 crisp, fresh-baked Vietnamese baguettes split and filled with the usual cold cuts—pork roll, head cheese, ham—while in a separate bag are all the fresh and moist elements—the pickled carrots and daikon, the cucumber spears, fresh cilantro, and plenty of green Thai chilis (way hotter than jalapeños).
Depending on the fillings, you can get 6 bánh mì for under $15. Instant picnic for you and your friends—some assembly required.
Tien Hung Oriental Foods
1112 E Colonial Dr Orlando, FL 32803 (map); 407-849-0205
About the author: J. Kenji Lopez-Alt is the Chief Creative Officer of Serious Eats where he likes to explore the science of home cooking in his weekly column The Food Lab. You can follow him at @thefoodlab on Twitter, or at The Food Lab on Facebook.