I'm sure it has an official name, but the neon green sign just reads: FALAFEL...so I'll call it: U6 Volksoper Falafel. If you've been to legendary Maoz http://www.maozveg.com/ then this is SORT OF similar. No, you can't keep refilling your sandwich as often as you like, but you can choose your toppings. They offer hummous, eggplant sauce, olives, etc. You can get a dürüm wrap or a pita. Costs 2,90. Is very tasty! At this moment, it's definitely my fav falafel in Wien.