Alinea and Grace ruined everything. And by “ruined,” I mean that we all got spoiled by the perfection of their upscale dining experiences. The result? We have come to expect an impeccable parade of gorgeous creations in our fine-dining restaurants, boundlessly imaginative but tightly calibrated, timeless yet somehow capturing the moment. Anything less is a failure.

For chefs still finding their footing, this is a dangerous game to play. The margin of error is so thin it can feel like little more than a radish shaving separates standouts like Oriole and Smyth from second-tier overreachers.

Brass Heart, a tiny Uptown newcomer, wants to compete. Chef-partner Matt Kerney, a Schwa veteran who earned a Michelin star at Longman & Eagle and appeared on Iron Chef Showdown, is clearly vying for a place at the big boys’ table with his pair of intricate 15-course prix fixe menus — one vegan ($145), one omnivore ($185).

The room, which once housed the critically lauded 42 Grams, retains a simple sophistication. Brass Heart’s kitchen may be open, but it’s out of view of the dining room (in contrast to 42 Grams, where chefs practically blew on your sunflower porridge for you). An actual brass heart hanging over the entrance gives way to metallic details and striking black-and-white photos of trending musicians like the Lemon Twigs. A hushed golden light imbues the 10 tables with an elegant glow. It all tastefully whispers, “This is a serious restaurant.” Sarah Traynor, the savvy beverage director who doubles as a server and is both omnipresent and omniscient, perpetuates that confidence.

And Kerney’s food definitely has the look. You know: pristine white plates painted with dribs and drabs; see-through apple slices arranged to lean against duck croquettes just so; rolled-up cucumber ribbons dotted with wondrous flowers that appear to have been plucked from a Georgia O’Keeffe watercolor.

At Brass Heart, when this artistry comes together in a cohesive whole, you get dishes like Ham and Eggs, a hunk of sausage made from acorn-fed pata negra pigs and served alongside a bulging poached quail egg on an island of toast in a jamón Ibérico consommé. Puncture the egg with your spoon and it sinks into the soup, one-upping the decadence of the ham wallowing in it. Five courses later, you’re treated to a cloud-soft fillet of halibut that’s been poached in duck fat, topped with a pine nut tuile and matsutake mushrooms, and half immersed in thick celery root cream. Grilled pickled onions cut the richness with thunderbolts of tart fermented flavor. Kerney also aces hallowed A5 Kobe beef, which he delicately caramelizes over Japanese charcoal, tops with chanterelles, and nests in an achingly lush salsify purée. The guy’s respect for the meat borders on worship.

And no one in Chicago has ever served more ambitious vegan food than Brass Heart. Diced pear floats in a velvety coconut mulligatawny. A shortbread disc made with sunflower and aquafaba (the liquid from a can of chickpeas) and sprinkled with crunchy carrot strips hides a whipped carrot purée. Both dishes, and many of the 13 others, push carefully curated unusual flavors hard and fast. I can’t stop thinking about the light but soul-satisfying bouillabaisse: proof that the dish’s famous power comes not from the fish but from the underlying flavors of Pernod, fennel, and saffron. Here they swirl together with a garlicky ajo blanco sauce meant to mimic the Basque fish stew called marmitako; the obligatory mini baguette makes for a brawny dipper in a world-class soup.

Brass Heart’s two menus interlock in fascinating ways. Take the bread course. On the regular menu, it’s a buttery, cinnamon-roll-like brioche ladled with honey, topped with fried chicken cracklings, and flanked by sweet pickle strips — a riff on the Southern tradition of serving fried chicken on white bread. The mirror-image vegan version Kerney and pastry chef Shawn Anderson-Calix have conjured up is virtuosic: This brioche, made with flax seed and vegetable-based butter — and boasting a texture miraculously indistinguishable from that of the nonvegan roll — is crowned with sweet-acidic pepper jam and a dusting of pepitas.

Alas, the procession of zillion-megawatt meteorites is interspersed with miscalculations and filler. The course before that magical halibut involved cappelletti chewier than bubblegum, stuffed with oversalty pheasant, and served in a broth so aggressively earthy it almost tasted like dirt. After the halibut came a shockingly bland seared lamb loin sitting atop ground hazelnuts and surrounded by beets and 25 dots of flavorless persimmon purée. Next came the Kobe beef masterpiece and, with it, hope. But the following course? A nutty Grayson cheese that had been transformed into a slice of cheesecake and paired, for some nefarious reason, with Dijon mustard foam: a marriage that makes no sense. The 15 courses began to feel like a Ping-Pong game between James Beard and an art school freshman. The three-and-a-half-hour meal’s rhythm, which was relaxed bordering on somnolent, only accentuated the problem.

Brass Heart may be the most promising, and frustrating, restaurant I’ve been to this year. We’re talking about a kitchen that ferments its own cashew cheese for three days and then uses porcini powder and dehydrated huitlacoche to make it resemble Humboldt Fog goat cheese. Kerney and his team take the kind of big chances that Oriole and Smyth — and, yes, Alinea — take. That’s admirable. But all too often, they whiff. At this level, that qualifies as a crisis. Brass Heart is walking a shaky high wire, with Michelin stars beckoning on the other end and no net below. I don’t know if I can watch.