The burger: Sure, Keg and Case Market is consuming all the Saintly City culinary oxygen — and rightly so, it’s an impressive-in-every-way achievement — but let’s not overlook the fact that Lowertown’s Market House Collaborative (a kind of mini food hall) recently introduced its final component.

The debut of Birch’s Lowertown is especially noteworthy — to followers of this blog, anyway — because it’s serving a phenomenally good burger.

This is a place that genuinely practices the “Collaborative” portion of its name. Octo Fishbar chef Shane Oporto has created the Birch’s Lowertown menu, and it’s produced in a corner of the Octo kitchen. The burger’s beef comes from the collective’s Peterson Craftsman Meats counter, and the bun is produced by another Market House player, the Salty Tart.

Yes, this is yet another entry in the already crowded pantheon of double-patty cheeseburgers. But this iteration really stands out, for all kinds of reasons, starting with the beef. Each burger utilizes meat from a single cow, a rarity that can comes from controlling production (the Peterson grass-fed operation is near Osceola, Wis.) and having the run of the butcher shop.

“We use as much of the cow as possible,” said Oporto. “And that’s reflected in the burger, because it does come out a little rich.”

A little? This is a profoundly beefy burger, in part because the semi-improvised grind utilizes whatever is on hand, including premium cuts.

“What I’m noticing from butchering over here at the butcher shop is that I’m able to grab short rib, rib eye, chuck, all the lead pieces from the round,” he said. “It’s really nice to use that whole cow. I’m not being too picky and choosy, and grabbing parts from 12 or 20 cows to create a certain formula. That’s why the flavor is so good, because you’re getting just that one cow.”

The thin patties weigh in at three ounces. They start in a semi meatball-ish state before being smashed on a hot flat top stove (that’s when they’re hit with salt and pepper, the only seasoning Oporto uses) and taken to a still-juicy and still-tender medium.

From there, the motto is simplicity. Oporto favors white American cheese (“Because it’s super-familiar, it goes back to the Big Mac,” he said).

Contributing to the caloric overkill is a prodigious amount of what Oporto calls “Fancy” sauce, equal parts ketchup and Kewpie mayonnaise (their attributes heightened with more salt) that is tinted an eye-catching coral — or is that salmon? — color.

(And why “Fancy”? “A little secret about me is that I really love the movie ‘Step Brothers,’” said Oporto. “It started with that. I was trying a bunch of different sauces, trying to figure out which would be the best. I was probably overthinking it. And then I was watching ‘Step Brothers,’ and there it was: ‘Fancy’ sauce. Just ketchup and mayonnaise. But we use Kewpie mayonnaise instead of regular mayonnaise.”).

There’s no lettuce, no tomato, no onion. But Oporto doesn’t avoid the produce section entirely: he builds a layer of crunchy refrigerator pickles. Five of them, every time.

“I ate a lot of burgers, trying to figure out the ratio,” he said. “With five, you get the right amount of acid to cut through what you’re eating.”

The bun is Salty Tart chef/owner Michelle Gayer’s patented (well, it should be, anyway) milk-enriched formula, and an instant classic. It’s sliced, buttered and toasted, and then the crown of the bun gets a quick browning toast, too. “To give it a little more flavor,” said Oporto.

That’s it, and this first-rate burger requires nothing more.

“We’re using quality meats, we’re adding quality ingredients and on top of that we’re using quality bread from Michelle,” said Oporto. It’s really that simple.”

Price: $14, and worth the investment.

Fries: They’re an additional $6, and recommended. Expect to encounter a highly shareable portion of matchstick-cut potatoes, fried to golden, lightly crispy perfection.

Also on the menu: Oporto features two other burgers. The “Brawt” is fashioned from pork, while the other features lamb. Both follow the same pair of 3-ounce, smashed-on-the-grill patties, with slightly different garnishes: bacon jam, fried onions and Cheddar on the former, roasted poblano peppers and a curry sauce on the latter. And because there's a brewery on the premises, beer pairings are a no-brainer. “A regular IPA would be nice with the Birch [beef] burger,” said Oporto. “Although he just came out with a new citrus sour — it’s a cross between an IPA and a sour — and it’s delicious.”

Where he burgers: “I’ll go to Saint Dinette, or I’ll go old-school and go to Matt’s,” said Oporto (pictured, above, in a Star Tribune file photo). “I have the best rapport with Adam and Laurel [Saint Dinette chef Adam Eaton and general manager Laurel Elm], so it’s almost like going over to a friend’s house to eat.”

Address book: 289 E. 5th St., St. Paul, 651-432-4677. Open 4 to 11 p.m. Monday through Wednesday, 4 p.m. to midnight Thursday and Friday, 11 am. to midnight Saturday and 11 a.m. to 11 p.m. Sunday. Burgers are available after 4 p.m.

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