"It's my birthday!" Doug Pagitt said as he warmly welcomed guests into his Edina backyard. "It's a surprise — for you, not me," he added.

Just a few hours earlier, I was sent an address — Pagitt's — for a burger pop-up I'd found on Instagram. After seeing a mouthwatering photo of a double-smash patty burger from Fumo Collective, I ordered two. The pickup location was kept secret until the day of the event. (Speaking of burgers, here's our burger bucket list for summer 2023.)

Walking up the driveway next to a barn-red house, there were no clues as to whose house it was or what we were about to find. Certainly not that we were about to attend a stranger's birthday party (without a gift, no less). Pagitt, a former pastor at a south Minneapolis church, guided visitors to a folding table full of snacks, coolers of beer and a karaoke corner. Children balanced on a tightrope course strung between two trees. Pickleball pairs played on a small court. A dog wearing a lei seemed to be smiling at us.

Way across the lawn was a black tent labeled Fumo Collective, with a bearded cook at the griddle. That was Steve Schirber, and he was the connecting thread that somehow tricked a bunch of social media-based burger fanatics to travel across the metro to celebrate a pastor's 57th trip around the sun.

"It's kind of culty, underground, you know?" Schirber said. "People love this idea of like, 'I've done all the restaurants, I want to go to some random person's backyard.' " He plopped eight clumps of ground chuck on the griddle and nudged little handfuls of sliced red onion into the nooks on their surfaces.

"It's a Minnesota potluck with people you don't know, but you're guaranteed this one thing," he said.

Schirber smashed the patties down with a heavy, smooth-sided stamp-like object — a burger press he had forged himself. A blacksmith and metal fabricator, Schirber became a live-fire cook in his own backyard. He caters events and puts on high-end farm dinners that showcase his skill with smoke and flame (fumo means smoke in Latin). But his burger pop-ups, which he hosted before COVID in his south Minneapolis neighborhood, are what he's known for.

"People just want us to make sandwiches," he said. "So we were like, all right, let's do this."

His burgers are two-handed affairs, with two patties, a thick hunk of bacon, onions that caramelize under the meat as it cooks, gooey cheese, an orange-hued sauce and curry pickles. Schirber's signature, thanks to his self-made smasher, high heat and a 20% fat blend: a crusty edge of almost-burnt beef.

"The idea is I want to get around the outside and get that lace," he said, smushing the outer edges into the griddle.

"I'm beyond the smashburger. I call it the 'smearburger.' "

When restaurants shut down early in the pandemic, Schirber used the kitchen at Ice House in Minneapolis to continue his burger business. When the kitchen there reopened, he stayed on as a chef for about a year. "And I realized I hated restaurants," he said.

So his backyard pop-ups are back, with one important parameter: Someone has to be willing to host.

Pagitt has known Schirber for two decades from their church, Solomon's Porch. He asked Schirber if he'd be willing to set up the griddle at his July birthday party. Schirber only requested a guaranteed minimum of burger orders — and the OK to open up the event to the public.

Who would have a birthday party and invite a bunch of burger-loving strangers from the internet to crash it? "Somebody that's really desperate for friends, apparently," Pagitt said, laughing.

In fact, he wanted to see all those new faces on his lush, manicured lawn. He used to hold weekly community dinners through the church, often with Schirber cooking. But that was pre-pandemic.

"I really like this kind of stuff," Pagitt said. "It feels like we're still kind of post-COVID. Like, oh my gosh, I haven't been at a party with 80 people, and I haven't met anybody new in so long. It's been a thing: How do people make friends? That felt like a piece of it."

The scene isn't for everyone. My native Minnesota companion was mortified to show up at a yard party without a dish to share. But by the time we had our last few bites of the eye-rollingly delicious Fumo burger, seated at one of Pagitt's patio tables, all pretense was lost. We'd inadvertently spent the evening with a bunch of interesting people — a blacksmith and a pastor, but also a butcher and a really good karaoke country singer.

We may not have had friends in common, but we had burgers in common, and that was enough.

Fumo Collective's next event is A Midsummer Night's Feast, a multicourse farm dinner with wine and cocktail pairings, July 22, in Wisconsin. Cost is $200; get information and tickets at fumocollective.com.