Who was Ruth West­heimer before “Dr. Ruth” became a cultural curiosity for her happy talk about sex and relationships? This diminutive child of the Holocaust captured the American imagination by dishing wisdom on penis size (it’s not too small), oral sex (use whipped cream) and what to do when a 5-year-old sees mommy and daddy naked on the living room floor (it’s a teaching moment).

Playwright Mark St. Germain found the sex therapist intriguing enough to explore her backstory in “Becoming Dr. Ruth,” which is on stage at Minnesota Jewish Theatre Company in St. Paul. Actor Miriam Schwartz, under Craig Johnson’s direction, portrays Westheimer.

St. Germain uses a familiar device in this formulaic one-person play. Ruth is moving from her Washington Heights apartment, where she lived with Fred Westheimer until his death in 1997. Packing up tchotchkes, photos, grabbing the odd phone call, she finds portals into her past.

She last saw her father when he was carted off by SS agents. She was part of the Kindertransport of Jewish orphans sent to Switzerland and after the war, she migrated to Palestine and became a sharpshooter in the Haganah. She lost her virginity at 17, married three times, had two children and was animated by a determined interest in education, which she credits to her father.

Schwartz’s Ruth argues that it was her belief in education and an imagination fueled by reading True Confessions magazine (“My Dickens and Shakespeare”) that got her into the sex talk business. “People need to talk about sex,” she said. So she listened. The combination of her frank pronouncements, doled out in a thick German accent, and her ebullient personality made her a celebrity.

Schwartz locates that quirkiness and voice in her performance. She is a good-enough actor that she persuades us to forgive the fact that she’s too young and pretty for the role. She mostly hides that, behind a wig and big glasses, and exudes a cute and coquettish style — the sort of vibe you get from a frisky aunt at a family wedding. Too, Schwartz’s technique — how she grabs a handful of books, hunches into a phone call, brings her character to the brink of tears — is excellent.

Johnson’s production is well made with Paul Epton’s lights, screen projections by Jonathan Gross and a messy apartment by designers Kirby Moore and Liz Josheff Busa. Johnson has such a good eye for nuance and detail, in stagecraft and performance.

I left Saturday’s sold-out performance wishing I could see Schwartz play this role in 30 years. But by then, will we still be talking about Dr. Ruth?