Street Food Tour For New Restaurant
Aside from local specialties, Philly's got a decent representation of international street foods. You could hit:
-Solo, the chinese kebab shop on 10th near Arch
-A Banh Mi shop (like QT, which is on the same block as Solo)
-A taco truck (in adition to Honest Tom's, there was a very authentic truck parked at 4th and Washington for a while; if it's still there, it could be worth a visit), or one of the taco joints near the Italian Market--somewhere where you can sample not just tacos but tortas and cemitas too.
-A Caribbean food truck, like the one across from 30th St Station where Bolt Bus picks up, and/or the Jamaican Jerk hut on South St.
-Falafel, like the famous truck at 20th and Market or a place like Maoz
-The Desi Chaat House on 42nd St. in W. Philly, specializing in the Indian street snack chaat
-Maru Global on 10th near Locust, specializing in the Japanese snack takoyaki--little stuffed crepe balls topped with bonito flakes, seaweed and sauces.
That's a start. Have fun eating, and good luck with your restaurant!
Truck: Honest Tom's tacos (especially fish tacos.) There are several Indian restaurants that serve "street type" fare. I would suggest perhaps hot breads in Montgomeryville, and Indian Hut on Street Road in Bensalem to get ideas of street food, fast food in the indian mode.