The titular Hamburg restaurant in Fatih Akin’s culinary comedy Soul Kitchen looks like a place where you might stop in for a drink if there was nowhere else available. But even when a quick survey of the parking lot and rail-yard surroundings indicates that there absolutely is not, you’d still be loath to order from the menu for fear of catching something. It’s not that the space is particularly grungy. In fact, it’s roomy and spare in a way that manages to be improbably Euro-chic while still low-key. But catch a glimpse of the harried proprietor and chef Zinos Kazantsakis (Adam Bousdoukos, also the co-screenwriter) slinging chips and burgers and schnitzel in the under-supplied, wildly unhygienic backroom, and you might have second thoughts.

It’s in this backroom that the film introduces a hairy underdog story that has buckets of promise. Zinos trudges through his days of serving bottom-end deep-fried fare and beer to his working-class patrons. The job doesn’t exactly inspire him, and to make matters worse, his bright-eyed, upper-class girlfriend, Nadine (Pheline Roggan), is about to decamp for a job in Shanghai. (Her protestations that a Skype account will keep them in touch doesn’t exactly win him over.)

As Bousdoukos performs Zinos’ angst with an inspired blend of moon-eyed sad-sackery and hair-pulling, his problems continue to multiply. Health inspectors come calling and he endures a visit from an old classmate (Wotan Wilke Moehring), now a yuppie real estate developer with all the morals of a piranha. Zinos’ convict brother Illias (the great Moritz Bleibtreu, playing winningly dumb as he did in The Baadar Meinhof Complex and Run Lola Run) arrives as well, announcing that he’s got a work furlough from prison predicted on the idea that he’s going to “work” at Soul Kitchen. This hardly helps Zinos’ mood, since it looks like all Illias is going to do is hang around with his deadbeat buddies and hit on the waitress, Lucia (Anna Bederke). The last straw is a debilitating back injury that sends Zinos to the ministrations of a beautiful physical therapist.

The story is buoyed by the appearance of Shayn (Birol Ünel), a chef at a gourmet restaurant in town who’s been canned for refusing to heat up a customer’s gazpacho (“Culinary racists!” he bellows). Quick with a knife and an insult, Shayn has no time for fools or unimaginative palates. A few twists of the screenplay deposit him at Soul Kitchen, where he takes Zinos’ humdrum ingredients and, with a few flicks of the blade and an eye for presentation, turns them into fine cuisine. The usual customers depart in droves, but eventually the local hipsters get wind of what’s happening down at Soul Kitchen and it becomes the hottest table in town.

For a brief time when the restaurant is humming along, Soul Kitchen makes perfect sense. Zinos is the sort of well-meaning fool whom it’s impossible not to cheer, and his obliviousness to the signals being tossed his way by the seemingly hard-edged Lucia, an artist in her real life, sets viewers up for a late-blooming but well worth-it romance.

Somewhere in the film’s middle, however, it begins branching out into unrewarding subplots. Akin’s decision to not indulge in the sort of lascivious food ogling expected in a movie about the rejuvenation of a down-at-the-heels restaurant. But the film inexplicably abandons its central theme, that good cuisine is literally food for the soul, and then flounders about, offering multiple underdeveloped storylines and some highly unfunny dives into a particularly German brand of low comedy.

Akin and Bousdoukos deserve credit for not making another self-indulgent yuppie metaphor about high-end dining: Hamburg’s industrial grit is far too apparent here for that. But the final product is undercooked.