German€€sachsenhausenDaily 11:00-00:00
Apfelwein Wagner proves Frankfurt tradition is a budget cuisine: Handkäs at €5.10 and Rippchen with kraut under €15 on Schweizer Strasse every day.
Try: Handkäs mit Musik at €5.10, Grüne Soße at €14.50
Tip: Order Handkäs and a Schoppen for the cheapest authentic Frankfurt dinner going; bread comes with it, and nobody hurries you out.
South Indian€€bahnhofsviertelDaily 09:00-22:30
Saravanaa Bhavan feeds Frankfurt generously for little on Kaiserstraße, dosa and thali portions that defeat most appetites at lunch prices and dinner alike.
Try: Masala dosa or the full vegetarian thali
Tip: The thali is the value play: multiple curries, rice, bread and dessert on one tray, refilled in the South Indian tradition.
Street food€westendMon-Fri 10:30-19:00; Sat 11:30-18:00; closed Sun
Best Worscht in Town remains Frankfurt's benchmark cheap hot lunch all week long, currywurst and Huck sourdough bread for well under ten euros.
Try: Currywurst with bread, heat level of your choosing
Tip: Level B is the sensible ceiling for first-timers; the bread is from Bäckerei Huck and soaks up the regret.
German€ostendShop Mon-Fri 08:00-15:00; Braterei Mon-Fri 11:00-15:00; closed Sat-Sun
Gref-Völsings sells Frankfurt's founding Rindswurst hot for pocket money, a 130-year institution disguised as an Ostend lunch window on weekdays.
Try: Rindswurst in a roll at the Braterei window
Tip: Weekday lunch only; the price has crept up over 130 years but remains one of the city's great food bargains.
Street food€bahnhofsviertelDaily 11:00-19:00
Frittenwerk's fresh-cut fries fill Frankfurt station-district lunch breaks for under ten euros, poutine gravy included and vegan dips on the board.
Try: Loaded fries or poutine
Tip: The plain fries with two house dips are the honest budget order; poutine upgrades still land under most lunch menus.
Burgers€€bahnhofsviertelMon-Sat 11:30-23:00; Sun 11:30-22:00
Der Fette Bulle keeps a serious burger and fries in reach of a Frankfurt lunch budget, portions built for the Kaiserstraße appetite at any hour.
Try: Cheeseburger with fries
Tip: The lunch hours before 12:30 dodge both the queue and the office rush; water is the local's drink here, and free-ish.