Crammed together sipping wine on the couch in producer Mike Wisti’s basement-based Albatross Studio, the members of Black Diet looked more cozy together than most young rock bands. Which was surprising, since this young soul-rock band mostly came together as complete strangers a couple of years ago via Craigslist and Facebook postings — the musical version of a successful online dating story.

“I didn’t know a thing about you for the longest time,” singer Jonathan Tolliver said to keyboardist Sean Schultz. “I thought you were from Iowa, and I thought you were Jewish.”

The couch erupted with laughter, as neither is accurate. However, most of the other facets of Black Diet’s story that have gotten around so far are true: The lanky, stalagmite-haired, Chicago-reared Tolliver indeed is a son-of-a-preacher-man (a fiery Baptist minister, no less); flaming-red-headed Iowa backup singer Margaret Keller (“Mugsy” to her bandmates) honed her sexy stage presence as a burlesque performer with Le Cirque Rouge; and yes, Black Diet was the act that made the biggest impression at last month’s Best New Bands showcase at First Avenue.

On stage that night, the sextet balanced an indie-cool garage-rock grind with a smoother, organ-heavy, groove-laden coating of soul music, applied to world-weary but libido-happy original tunes (such as “You Did It to Yourself”) and an absolutely rapturous cover of LCD Soundsystem’s“All My Friends.”

With “the adrenaline from that First Ave show still in our system,” the sextet entered Wisti’s studio two weekends ago to try to capture their live energy for their debut album, due in April.

Headed to 7th Street Entry for’s fifth annual Are You Local? contest next Thursday — and the main-room stage again if they win — the band is even better thanks to that studio experience, said bassist Garrison Grouse: “Recording sort of teaches you how to communicate with each other better and pay more attention to the different parts, and to do all that without ego.”

Not that ego is entirely ruled out in Black Diet, whose members are all under 30. There’s a cocky, Jagger-ian swagger to Tolliver’s stage presence, which he doesn’t deny. “I’m a confident person,” he admitted, adding glibly but truthfully that the sexiness in their songs also comes from the fact that “a lot of our songs are about sex.”

With an ambiguous band moniker — it’s a term for starving prisoners to death — Black Diet grew out of the even more uncomfortably named group JT & the Sloppy Seconds. “A lot of people already told me they didn’t like the old name,” Tolliver recalled, “then we were booked to play an ACLU gig, and they said, ‘No way.’ So I put a stop to it then.”

A key ingredient is Keller as backup vocalist. She adds a sensual tone to Tolliver’s vibrato vocals and sexually laced songs, and plays a prominent, delectable role on stage, too. She credits her burlesque experience: “It’s important in burlesque and cabaret performances to make sure you look good, and make sure you make eye contact and connect with people.”

She, too, was found through Craigslist. Tolliver knew the obvious question before it was asked. “Yes, we were lucky,” he smirked. “The ad didn’t ask for a sexy redhead, but we were definitely looking for it.”

The couch erupted again.