Much has been written over the last few weeks - by me, in fact - about the region's current vegan revolution. These are days of feast and bounty for the "plant-based" eater in Philadelphia.

But the movement's inevitable push into the mainstream, now rumbling unstoppably forward like the Market-Frankford El train that rattled overhead as I stepped into the Front Street Cafe, had come almost full circle as I sat down and held the menu at Fishtown's latest, hottest, feeling-good-about-the-'hood place.

It's not simply that there are plenty of meat-free and dairy-free options at this sharply designed and sprawling all-day cafe-restaurant, where the scrapple is made from mushrooms and the "queso" is really carrots pureed with cashews and nutritional yeast. The omnivores, for a change, are the ones who get the special icon treatment on the menu's margins, with cute little bird symbols, piggies, and hunks of holey cheese denoting dishes that might be of interest to those who still dabble in proteins of the animal kind.

Our waitress clearly was not one, only barely suppressing a look of horror behind her smile when I asked why the pecan-crusted hon shimeji mushrooms tasted vaguely of fish: "I wouldn't know -," she said, her multicolored fashion dreads quivering with dread. "I've never eaten seafood in my life."

After similar non-replies to other queries about menu hits like the fried chicken sandwich, burger, and miso salmon ("I've never eaten meat, but I hear they're good"), I sank a little lower into my seat, gripped my kombucha-infused cocktail tighter, and proceeded to munch ahead.

Exactly why those mushrooms had a marine tang remains a mystery, as there's no fish (or even seaweed) in the recipe for the batter (rice flour, almond milk, mustard, and ground pecans) that's supposed to crust beech mushrooms. What is clear is that this nutty crust was nowhere to be seen on the plate I was given, and the long-stemmed mushrooms that came to my table naked and shriveled atop a polenta cake with saffron sauce had the unexpected chewy texture of mushroom jerky. A good bar nibble, maybe, but not something I'd like to devour in entrée portions.

Then again, the picture of beautifully nut-crusted oyster mushrooms taken later by photographer Michael Bryant for this review looks like something I might actually want to eat. But a vexing streak of inconsistent cooking was a persistent theme at the Front Street Cafe, where a gorgeous space and smart concept were continuously dimmed by a lack of steady execution.

In a neighborhood whose rapid emergence was built on gastropubs fueled by pork bellies, burgers, and beer, I understand why a more health-forward approach would be a breath of fresh air to the area's new wave of millennial settlers. With affordable prices topping out at $18, a coffee bar serving Counter Culture beans, a cocktail bar pouring craft brews, and drinks with fresh mixers and local spirits, plus a full repertoire of breakfast, lunch, and dinner menus, this cafe has the appealing aspect of an all-day, please-everyone hybrid juggernaut.

Just a block from the Girard El station, this project from developer Liam Larkin and Nicole Barclay is a potential keystone to new growth along Front Street. It's such a good-looking place, this historic building beautifully rehabbed into a vast bilevel complex of brick and hardwood floors, plus a massive patio for al fresco dining. It's the kind of hub everyone's rooting for.

But its massively ambitious scope only shows how hard it is to execute a concept that aspires to be everything to everyone.

Under chef Chris Rubinstein, a vet of both vegan and mainstream kitchens, there were a few things the cafe did well. (And more than a few, while he was on vacation, that it didn't.)

I actually loved that hearty mushroom scrapple, an earthy, crispy cake bound with lentils, flax seeds, and herbs. Set atop an everything-spice "Philly muffin" topped with a citrusy hollandaise and a mound of tasty scrambled tofu (firmer chunks than the typical bean curd mush, and tinted yellow with sweet bell pepper powder rather than the usual turmeric), this is a healthy start I'd take a train for. But the house-cured gravlax on the side was oily, overripe, and fishy.

There wasn't much "queso" in the Fishtown Queso app. But that may have been a good thing. The faux-whiz made from pureed carrots (and cashews and potatoes) was a pretty orange accent atop a satisfying crock of smoked black beans with tortilla chips for dipping.

The dry-aged burger had a deep beefiness that proved this kitchen can go full-carnivore when it needs to, topping it with crisp blades of smoked Nueske bacon, Mahon cheese, and garlic-thyme aioli. But it took the kitchen two tries to get that six-ounce patty close to medium-rare.

The juicy fried chicken sandwich would have been perfect had its crust flavorful with buttermilk and Crystal hot sauce not been overfried dark brown. The duck breast was also tasty, but the "jus" on the plate looked more like pooling pink blood, and the lavender almond puree was too pasty to become the sauce that duck needed.

Other dishes had fewer redeeming virtues. The mushroom pho had possibilities with an anise-infused broth and a meaty pad of smoked portobello. But there wasn't enough of that broth (which just barely moistened the noodles), and it took a sour turn with the unfortunate addition of pickled jalapeños (a misguided cross-utilization from the tostada bowl) as opposed to the usual fresh chiles. Even worse, a wad of alfalfa sprouts inadvertently subbed for mung beans smelled like wet socks as it sank into the murky broth.

The seed-crusted mahimahi atop tacos had seized up into curling fists of overcooked fish (topped with achingly sour laces of badly pickled onions). We liked the fake "meatballs" filled with moist lentils, but the spaghetti squash below them ripped to mush when we tried to stir in the chunky romesco sauce. The attempts at tricky Hasselback potatoes - whole spuds deeply sliced crossways into thin but still attached rounds, which ideally turn crispy on the outside but still fluffy at the center - have wisely been abandoned.

In some cases, though, it was just carelessness, like the Super Green hemp smoothie that had been so sloppily blended a fistful of chia seeds clumped against the bottom of the pint glass like a terrarium.

"Oh, that's the house granola!" our waiter vamped while the handlebars on his waxed mustache curled tighter and he sank deeper into the fib. "Some people just chug it when they get to the bottom."

No, I think we'd already hit bottom at the Front Street Cafe. When it finally gets a handle on those grand ambitions and begins its inevitable rise, it will be an exciting new addition to Fishtown, indeed.

Next week, Craig LaBan reviews Tredici Enoteca in Midtown Village.

claban@phillynews.com