Some bands are born to back a singer. Others are launched to jump-start the members’ social lives or maybe earn a little money.

Mostly Kosher, a popular Southern California Jewish-music ensemble, got its start five years ago because a well-meaning teenage musician bluffed.

“I was playing piano for a wedding gig at a temple in Orange County and shmoozing with these beautiful octogenarians,” Leeav Sofer said during a phone interview. When they discovered he was Jewish and also a clarinetist, they asked, “Do you play klezmer?”

The 19-year-old Sofer didn’t know a freilach from a freight train, but he knew a gig. “Of course, I play klezmer,” he said. “Of course, I have a klezmer band.”

Mostly Kosher makes its Northern California debut this weekend.

The women immediately hired his imaginary band for a congregational gala.

“I hopped in the car, got on the freeway and called every great Jewish musician I knew,” Sofer said, “and the guys I knew that were talented and could hang and could pick up a new genre of music. One gig led to three,” then more shows in and around Los Angeles, including the Skirball Cultural Center and John Anson Ford Theater, as well as a self-titled 2014 CD.

Mostly Kosher, calling itself a Jewish cultural revival band, makes its Northern California debut this weekend, with performances throughout the Bay Area.

“We’re not a klezmer band,” Sofer explained. “What I and the other musicians really appreciate is that there are so many different kind of influences, from tango to hip-hop — taking this traditional music, which we really appreciate and honor, and figuring out what’s our take on it.”

Nor are all eight band members Jewish. Hence the “mostly” in the name.

The band’s CD features not only well-known Yiddish theater and klezmer tunes, including upbeat freilachs, but also Hebrew and Sephardic songs played in a range of styles — propulsive Latin rhythms, swinging West Coast jazz and sensitive balladry — with expressive singing featured in half the songs.

Violinist and co-bandleader Janice Mautner Markham added that music is “so complex. Leeav literally writes what he wants to hear. We really all have to be so up on our game.”

But a Mostly Kosher show isn’t just about making music. It also includes skits from the band’s original klezmer-Yiddish radio hour, with Mautner Markham playing the role of Rachele the Matchmaker.

“It’s a character I’ve pulled out — part my grandmother, part my grandmother’s friend Blanche,” Mautner Markham said. “I’m always trying to find Leeav a girl. That’s the shtick.”

Rachele suddenly appears, commenting with a thick Yiddish accent, “I can tell through the phone that you look a little thin. You need to have a bagel.”

The bandleaders developed their radio show after listening to old programs and re-creations, researching in books and audio materials at the UCLA Film and Television Archives, and studying at the 2014 KlezCanada summer Yiddish cultural workshop. Mostly Kosher will present the full radio show at Tiburon, with selected skits at San Francisco’s Red Poppy and Berkeley’s Ashkenaz.

At Ashkenaz, the band will introduce a new genre-bridging song. “It’s called ‘Crawdad Bulgar,’” Sofer said. “It’s our mashup of an American folk song, ‘Crawdad Song’ with the Yiddish tune ‘Reb Dovidl,’ which we turn into a Bulgar version. It takes a pretty Gogol Bordello Gypsy-punk kind of turn. I use hambone and body percussion.”

In addition to Sofer on vocals, clarinet and piano, and Mautner Markham on violin, the band features Michael Bolger on trumpet and accordion, Eric Hagstrom on drums, Mike King on trombone, Adam Levy on bass, Casey Solow on vocals and substitute guitarist Skip Heller.

Mostly Kosher performs Oct. 23-26 around the Bay Area. See Calendar/Music or www.mostlykosher.com for details.