Like one of her favorite romantic comedies, “Crossing Delancey,” writer-director Rachel Israel’s narrative feature debut “Keep the Change” is a New York love story with a tangible Jewish undercurrent.

The romantic duo in the San Francisco Jewish Film Festival’s opening-night selection readily self-identify as Jewish, but they share another quality that for most people primarily defines them: David and Sarah are on the autism spectrum, and so are the amateur actors who play them, Brandon Polansky and Samantha Elisofon.

Refreshingly honest and sexually straightforward in its portrayal of the way people with autism interact with each other, with their families and with strangers, “Keep the Change” received two prizes, including the top U.S. narrative jury prize, when it premiered at the Tribeca Film Festival in April.

“A few of the characters are naturally unfiltered in the way they talk about sex, and I thought it was a beautiful and fun aspect of the characters,” Israel explains in a phone interview from New York.

“A lot of depictions of people with autism shy away from sex, and I think it’s important to show that people on the spectrum have sex lives,” she says. “To shy away from it is in some way demeaning or infantilizing.”

“Keep the Change” receives its Bay Area premiere when it opens the festival on Thursday, July 20 at the Castro Theatre in San Francisco, which will be followed by additional festival screenings in Palo Alto, Albany and San Rafael. The filmmaker and the two lead actors are scheduled to appear in person at the opening-night showing.

Israel spent her childhood in New Jersey and her adolescence and teenage years in Florida before pursuing her undergraduate degree at the Rhode Island School of Design. She moved to New York for her graduate study in film at Columbia University, where she refocused her first screenplay from a drama about David’s family to an endearing, awkward and rocky love story between David and Sarah.

Israel set about making a short film, and discovered a community of people with autism at the Manhattan Jewish Community Center on the Upper West Side. She cast Brandon and Samantha, and some five years later asked them to reprise their roles for a feature.

“Brandon’s search for love and companionship, and possibly sexual experience, is a defining part of his personality,” Israel says.

“When I met him I didn’t know he was on the spectrum, and even for a while I didn’t know until he told me. When he told me he had autism, it was an awakening, because I thought [of an autistic person as] someone like Dustin Hoffman in ‘Rain Man,’ someone who shies away from contact. And that was very much not the way Brandon was.”

His character’s Jewishness is front and center, which may feed into some viewers’ judgement of his ostentatiously wealthy parents, played by Jewish actors Jessica Walter (Lucille Bluth in “Arrested Development”) and Tibor Feldman. Sarah’s Jewish identity is much less pronounced, but it could be a plus — in theory — in winning David’s parents’ acceptance.

“He is quietly desperate to have a girl, so it wouldn’t have stopped him at all [if Sarah wasn’t Jewish],” Israel says. “But it’s a big thing for many Jewish parents for your kids to stay in the tribe. He thinks that it will please his parents.

“But more than that, for himself he wants some traditional things for his life. He wants a permanent loving relationship. I think he thinks that should be marriage. He very much wants the things that he’s seen his peers from childhood acquire, and he doesn’t understand why he shouldn’t have them.”

Audiences will probably conflate Brandon with his character (David) and Samantha with hers (Sarah) more than they typically do with actors and the characters they play. In reality, David and Sarah are fictional versions of the real people.

“We wrote it in collaboration with the cast, but they are playing fictional characters,” Israel emphasizes. “They are not playing themselves. We’ve created characters that had some of their tendencies, while other things were different. They could definitely draw upon who they were to inform their characters.”

After Tribeca, Israel screened “Keep the Change” at the Los Angeles Film Festival and, earlier this month, at the Karlovy Vary Film Festival in the Czech Republic. Her grandfather, a financial supporter of the film who escaped Czechoslovakia at 14 on one of the kindertransports organized by Sir Nicholas Winton, attended the latter festival with Israel.

All in all, Israel devoted six years to “Keep the Change,” from screenplay to the short film to the feature-length version. She’s eager to embark on a new feature, and primed to explore new territory.

“The simple answer is there’s not a sequel right now,” she says. “I don’t think the next chapter is a simple one for these characters.”

“Keep the Change” screens at 6:30 p.m. July 20 at Castro Theatre, S.F.; 6:40 p.m. July 23 at CineArts, Palo Alto; 6:15 p.m. July 30 at Albany Twin, Albany; and 6:45 p.m. Aug. 5 at Smith Rafael Film Center, San Rafael. (Unrated, 94 minutes)