Nearly 100,000 New Orleanians were displaced to Houston. Their biggest complaint is the lack of a good poor boy sandwich anywhere in that city. (well maybe that's a stretch, but the sentiment has been recorded). What's the problem?
First you need great French bread.
Leidenheimer's French Bread is the best because of the shape of the baguettes, the crunch of the crust and the softness of the interior. There are plenty of other bakeries around town that make a passable loaf. Baked locally in New Orleans this ingredient has to be fresh. French bread does not last. Even 24 hours is too long. The top bakeries ship three times a day. Wrapping in plastic just makes it droop. The secret seems to be the ovens that generate just the right temperature and thermal inertia to make the crust crisp while the inside is light and tender.
Then you need the main ingredient (the meat). Roast beef with gravy is a favorite. Seafood gets others going. Sausage is popular, both hot and Italian. Cold cuts will do in a pinch. Some people even think French Fries with brown gravy makes a great po-boy.
Dressing a sandwich is of course adding Blue Plate mayonnaise, lettuce (some like shredded cabbage), tomato, pickles. Seafood also needs a squeeze of lemon, tomato ketchup and a sprinkle of Tabasco. Wrap it in paper and let it breath for an hour to bring the flavors to a peak or just dig in right away.