If the name Jim Christiansen sounds unfamiliar, it won’t be that way for long.

The Eden Prairie native is a case study in how to successfully navigate the tricky path to culinary rising stardom. Track this progress. First, he educates himself in top-flight work environments, including La Belle Vie. Second, he emerges relatively unscathed from a risky turnaround, the ill-fated Il Gatto. Finally, he lands a pressure-cooker position at a high-profile project. And then he flourishes.

Much of the chatter surrounding Union has been consumed by other details, and why not? It’s a great story, generating a seemingly endless string of headlines: New life for a long-dilapidated downtown corner. The rooftop patio to end all rooftop patios. Kam Talebi, restaurateur with the golden touch. Cocktail czar Johnny Michaels does it again. You get the idea.

But when that buzz dies down, it’s Christiansen who will ultimately become the keeper in this tale. Because the restaurant is powered by corporate dining dynamo Kaskaid Hospitality, I feared that the company’s market-tested, something-for-everyone approach — wildly successful in its Crave book of business — would dull the edges of this one-of-a-kind real estate. But Christiansen imbues much of his cooking with personality, subtlety and technical acumen.

The lengthy dinner menu is organized by snacks, appetizers, shared plates and entrees, with prices escalating while traveling down the list. Starting at the top, I can’t imagine dropping in and not ordering the dish that amusingly embraces two trends. Yes, bacon and doughnuts, or in this case, surprisingly light and tender yet deeply savory doughnut holes. They’re terrific, just $6 and a harbinger of good things to come.

At least so I thought. My first dinner, a month after the restaurant’s mid-November opening, was uneven. Highlights included divine lamb meatballs served on pretty zucchini ribbons, crispy fried smelt playing against bitter endive and pops of citrus, and dense Kabocha squash-filled ravioli dressed with a nutty, clove-scented butter and crispy sage, with a splash of reduced apple vinegar to counteract the squash’s inherent sweetness. The combination was so entrancing that I can vividly recall every detail, three months later.

Opening month jitters?

But there was a near-equal number of flops: unpleasantly rare roast duck, overcooked chicken and a dreary, uninspired cheese plate. The host stand had no evidence of our made-over-the-phone reservation, waits between courses began to border on endless and the less said about dessert, the better. And the sound level on the jam-packed rooftop was migraine-inducing.

But subsequent returns in late February yielded vast improvements. The menu’s land mines were fixed or eradicated altogether, although with them went some of Christiansen’s most ingenious ideas, including crispy sweetbreads with pillowy dumplings, and juicy scallops, their tops seared to copper and paired with thinly shaved cauliflower, a beautiful white-on-white presentation accented by garden-green sage.

The good news is that the replacements are even better. Scallops, for example, still boast that same deep caramel burnish but are now paired with similarly melt-in-your-mouth pirogi and a teasing mustard sting. Perfect.

I could die a happy man after greedily consuming the eggy, pappardelle-like pasta, tossed with thin shavings of cumin-cured lamb belly and a tangy tamarind-vinegar sauce. Ditto the spreadable butter-enriched chicken livers, set in a cute jar that’s capped with a gently flavorful maple gelée.

I crave the meaty mussels, steamed in a nose-tickling lemon verbena broth. Or the gorgeous sunny-side-up egg, laid out over sweet/spicy slow-braised oxtail and garnished with a flurry of herbs; when it comes to herbs, Christiansen’s instincts are right on the money. Or the over-the-top suckling pig, nurtured in a confit of duck fat. Or the kind of roast chicken that a chicken lover hopes will emerge from the kitchen but rarely does.

Sure, there were a few aesthetic mistakes: The rainbow trout, its preparation seemingly complicated for complication’s sake, tasted primarily of the grill, and the pot-roast-like veal shaped into what resembled a hockey puck (“it looks like a veggie burger,” my friend said). Another oddity is the difference between the street level and rooftop menus. The latter is an abbreviated version of the former; shouldn’t it be the other way around?

Weekday lunch, served on the rooftop, offers an instant replay of dinner’s greatest hits, including several lovely, sharply executed salads. Christiansen also places a couple of deluxe burgers into the mix, including an oxtail version destined to become a classic. But he makes a misstep by offering sandwiches and tacos that don’t set themselves apart from equivalents available (at lower prices) at several nearby food trucks. The setting — more on its splendors in a moment — deserves better.

Pastry chef Alexandra Motz — another La Belle Vie vet — has replaced the drearily predictable offerings of her short-lived predecessor with inventive, eye-grabbing sweets that skillfully extrapolate textures and flavors. As to the (occasionally overpriced) cocktails, Michaels is to mixology as Tchaikovsky was to melodies, drawing from a bottomless supply of winning ideas.

Seriously, wow

When faced with the choice of remaining on the street-level dining room and bar or going upstairs, it’s a total no-brainer. To the roof!

Think of it this way: The main floor is Kelly Rowland, the rooftop is Beyoncé. It’s not that the first-floor space isn’t without appeal (both are designed by Shea Inc., which occupies the building’s second floor). With its understated chocolate-and-gray palette, it’s a muted iteration of the Crave design template, a welcome development. But it in no way offers clues for what lies above.

The rooftop is a world apart, a soaring, energetic and crisply elegant space that’s so transporting that the IDS Tower, our reassuring compass, is the only indicator that you’ve remained in Minneapolis. It’s a thriller at lunch, when the eye sees only sky and skyscrapers (even on a cloudy day, it’s the architectural equivalent of a Seasonal Affective Disorder light therapy lamp). By night, it’s urbanity personified, and an instant point of pride for the city.

If the Vikings aren’t using Union’s retractable glass barrel vault of a roof as a prototype for their new billion-dollar sports palace, they should, because creating a year-round indoor-outdoor environment just might be the smartest investment Talebi has ever made.

That, and steering money into Christiansen, Motz, Michaels & Co., rather than relying upon his already-paid-for Crave formula. Union’s singular venue deserves nothing less.


Follow Rick Nelson on Twitter: @RickNelsonStrib