The burger: I dropped in on the Oak Grill earlier this week for a late lunch, and given what I knew was probably going on four floors below in the store's eighth-floor auditorium, the dining room seemed to be the very definition of the calm before the storm. It wasn't exactly busy; I counted maybe a dozen fellow diners, although that was hardly unexpected given that it was 1:45 p.m., late for work-ethic Minneapolis. Still, being led to that premium near-the-fireplace seat felt like a gift, because within a few days the restaurant is going to briefly become one of the toughest tables in town, thanks to the annual event that I will forever call the Dayton's-Bachman's Flower Show.

Of course it now goes by a different and rather tongue-twisting name: Macy's Flower Show Gardens by Bachman's, and when it opens Sunday (and runs, free, through April 6), many of its visitors are going to find themsleves at the Oak Grill. That's sugar-coating it. More like, they're going to inundate the Oak Grill.

It's not a stretch to imagine that a significant percentage of those azalea- and tulip-seekers will stick to the restaurant's department store basics: chicken pot pie, meatloaf, an excellent wild rice soup, almond-crusted walleye with mashed potatoes and other comfort-food fare. And big, doughy popovers, the house specialty.

But for those in the mood for something a tad more contemporary, it's a relief to know that the Oak Grill isn't a museum, preserved in some amber-hazed fog from yesteryear. Case in point: the BLT Jam Burger, which manages to tap into so many burger crazes that it could be taking its cues from the trend-conscious Oval Room during its pre-Macy's heyday.

Pretzel bun? Check. A criss-cross of crisp, applewood-smoked bacon? Yep. An unexpected cheese? Uh-huh (it's a semi-soft Monterey Jack that's marbled with tangy blue cheese, and it's terrific).

In place of the standard-issue raw or caramelized onions, there's a generous flourish of crispy fried onions (truth to tell, maybe too many; save your deep-fried appetite for the fries), a welcome textural surprise. A giant lettuce leaf adds color and subtle crunch. Then there's the marvelous thin-sliced refrigerator pickles, so juicy and crunchy. I'm still kicking myself for not asking for extras.

Best of all, garnish-wise, is the T portion of this BLT-hamburger mash-up. No dreary, off-season tomato slices for this one. Instead, the kitchen wisely cooks down tomatoes, concentrating their flavor into a thick, slightly sweet jam then packing it with fresh herbs. It's swiped (not generously enough, at least for my tastes) across the bottom of that buttered and gently toasted pretzel bun, and it's a marvelous solution to the eternal Lousy Winter Tomato issue – honestly, when tomatoes are this cottony and flavorless, why serve them any other way?

It's intentional that I'm leaving the patty for last, because thinking about it makes my shoulders shrug. Love the deep char flavor, and the way it stretches to the bun's edges (this is definitely a knife-and-fork burger). But each bite was crying out for salt, and my medium-rare request arrived on the far side of medium-well.

Still, this Oak Grill regular was impressed. Who knows? On my next visit, I just might skip my usual chicken salad and order the burger. For this creature of habit, that's saying something.

Price: $12.95.

Fries: Included. Super-crisp, wonderfully salty and freckled with chopped parsley.

Helpful tip: During the flower show, plan ahead and make a reservation, especially during peak hours.

Bonus: As a flower show extra, Oak Grill diners will receive a free German chocolate cupcake with the purchase of any entree. The bar is adding a half-dozen floral-themed cocktails, including a shake of rum, hibiscus syrup and lime juice poured over ice, and an elderflower liqueur blended with sparkling wine and a splash of soda. Nice.

Bonus, part 2: During the flower show, Macy's will be hosting a series of cooking demonstrations in the store's lower level cookware area. On March 24: chefs from Marin Restaurant. March 25: Macy's chef Susan Johnson. March 27: Union Fish Market chefs Lucas Almendinger and Shane Oporto. March 28: Miami star chef Michelle Bernstein. March 31: Macy's chef Marie Hanson. April 1: bakers from Sweet Retreat Bakery. April 2: chef Erik Weed from Rinata. April 3: Macy's chef Joe Studenburgh. All demonstrations begin at noon and are free and open to the public.

Parting shot: Along with the service staff's friendly familiarity, one of the reasons why I enjoy visiting this downtown classic is the opportunity to bask in its reassuring timelessness. The sedate dining room – paneled in oak, of course, and outfitted with crisp white tablecloths -- hasn't changed much since the Dayton brothers opened the 12th-floor restaurant in 1947. In this post-Dayton's world, the sales floors aren't what they used to be, but the store's food division has succeeded at keeping the Oak Grill in tip-top shape, an effort that this tradition-minded diner appreciates.

Address book: 700 Nicollet Mall, Minneapolis, 612-375-2938. During "The Secret Garden," the Oak Grill is open for lunch and an early-ish (to 7 p.m.) dinner daily.

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