The burger: When FireLake Grill House & Cocktail Bar went through a much-needed cosmetic overhaul earlier this year — a part of the multi-million dollar overhaul of the Radisson Plaza Hotel in downtown Minneapolis, now called the Radisson Blu — the powers that be kicked around various promotional ideas for getting the word out. I vaguely recall a press release crossing my desk, but I definitely remember the 12-year-old restaurant's much more attention-getting strategy: A food truck, which quickly became a popular Marquette Avenue attraction during its brief life.

For that meals-on-wheels promotion, chef Jim Kyndberg — if that name is familiar, it's because he was the creative force behind the late, lamented Bayport Cookery — was looking to ignite some culinary fireworks. One solution was a burger with a taste-of-the-region emphasis. Not just in terms of ingredients, either. "Being the Minnesota-focused restaurant that we are, I felt compelled to do a stuffed burger," he said.

Yes, a Juicy Lucy, of sorts. For the name, he turned to a Gopher State legend — Paul Bunyan — and christened his effort the Blue Ox Burger (more on that in a moment). It sold like gangbusters, and with good reason; it's a phenomenal burger.

Like all memorable burgers, this one piles on the complementary flavor layers, starting with the beef's brawny, ultra-rich bite, which of course comes with a backstory (come on, this is Burger Friday, after all). In a previous job, Kyndberg had collaborated with the premium beef go-to folks at Peterson Limousin Beef to develop a chuck-brisket-short rib grind, inspired by the much-lauded hamburger formula created by Pat La Frieda Meat Purveyors. It left such a favorable impression that Kyndberg filed it away for future reference, remaining on the lookout for a place to re-introduce it. (I think the results are pretty close. Taste-test for yourself, with a visit to Lake & Irving, which imports the La Frieda product for its precedent-setting burger.)

Each prodigiously hefty patty is grilled over hickory and mesquite, and the woods' smoke sneaks into but doesn't overpower the fat-laced meat. And talk about grill skills: At my first indelicate chomp, the thing just ran juices. A second, even messier bite later, and I reached for my knife and fork.

This isn't your basic bare-bones Juicy Lucy, not by a long shot. For starters, there's an under-the-patty layer of bacon-onion marmalade. And yes, it's as eye-rollingly delicious as it sounds, with dashes of maple syrup and vinegar staging a low-key sweet-and-sour tug-of-war.

I love how Kyndberg isn't afraid to go all-in on the Paul Bunyan lore. Literally. That tender, crazy-juicy shredded beef that adorns the top of the patty? It's a ragu of, yes, oxtail. "As in, Babe the Blue Ox," he said with a laugh, referring to the legendary lumberjack's cobalt-tinted bovine buddy. "I couldn't resist."

Heh. As for the cheese, it's the tangy, salty, cave-aged pride of Faribault, Minn., and there's plenty of it. Staying true to the Juicy Lucy spirit, Kyndberg sneaks a tweak into the crumbly cheese. "It doesn't have the right 'goo' factor for a stuffed burger," he said. "So we grind up a good local cheese curd and mix it with the Amablu. That's what gives it that meltiness."

It works. The final keeping-it-local touch? A spear, fashioned from -- wait for it -- bison jerky. Wait, one more: A real beauty of a brioche-style bun, from New French Bakery.

For those on a Juicy Lucy quest, this is one for the books. Consumers are clearly in agreement, because Kyndberg reports that the Blue Ox Burger competes, sales-wise, with the menu's popular basic cheeseburger. Me? I can't believe that it's not outselling its plain-Jane sibling two to one.

Price: $15 (and, to reiterate: downtown only; not available at the restaurant's Mall of America location, although it should be).

Fries: Included. They're skinny, crisp, salty, skin-on and wonderful. They're even better with the kitchen's smoked ketchup. Kyndberg shies away from revealing too many details ("It's a secret blend," he said with a laugh) but he does cop to "about seven different spices," including the identity of the dominant flavor note: smoked paprika. Here's how high it ranks on the Condiment Judgment Scale: I spent a few minutes trying to figure out a way to get the leftovers home without stealing the cute little serving crock. "In the past, whenever I've presented house-made ketchup, we're always overwhelmed with requests for Heinz," he said. "But with this ketchup, those requests are few and far between. One of these days, we're going to have to bottle it." Yes, he should.

Hunting season: Kyndberg is one of the few chefs in town who finds a regularly scheduled slot for game on his menu. Right now that means dishes along the lines of venison Bolognese, elk chili, pheasant croquettes and, on the charcuterie board, a smoked goose breast. Nice.

Knowing when to stop: Don't expect to see another burger on the FireLake menu. "I think we're going to stop here," said Kyndberg. "I have four on the menu, and I don't think I want to turn us into a burger joint." The other three? A turkey burger ("using the grind from Wild Acres, we season it in house," he said), a walleye burger and the previously mentioned classic white Cheddar cheeseburger; all are first-rate.

Address book: 31 S. 7th St. (in the Radisson Blu hotel, between Nicollet Mall and Hennepin Av.), Mpls., 612-216-3473. Open 6 a.m.-midnight Monday through Friday, 6:30 a.m.-midnight Saturday and Sunday.

Talk to me: Do you have a favorite burger? Share the details at rick.nelson@startribune.com.