Jessie Ware performs at Washington’s 9:30 Club on Tuesday. (James Moriarty)

Jessie Ware flashes back to a Dublin gig last year. The bass bumps, the lights flare, the British singer squints into the crowd. “And there’s this couple slow dancing together like nobody else was in the room,” says Ware. “I thought, ‘Oh, sod me. I just want to watch them!’ It was soromantic. Agh! It killed me!”

Funny, though. This was exactly how Ware had intended it.

The 28-year-old Londoner — who performs at Washington’s 9:30 Club on Tuesday — says she conceives her elegant R&B songs by visualizing high school gymnasiums filled with balloons, bunting, pheromones and expectation. “I’m mad about teen films that always end up at proms,” says Ware, over the phone, overseas. “[Songwriting] is, like, me playing teen flicks in my head.”

Ware’s ability to capture the heat of an adolescent blush with her cool, Sade-inspired alto speaks to the gorgeous in-betweenness of her music. Her debut album, “Devotion,” works as well on a Saturday night dance floor as it does during a Sunday night bubble bath.

And with Adele’s “21” refusing to extract its fangs from Billboard’s jugular after 98 weeks on the charts, Ware is one in the latest wave of British soul chanteuses hoping to make a dent in the States this year. A five-song teaser EP, “If You’re Never Gonna Move,” lands in the United States on Tuesday, while “Devotion,” released in the United Kingdom last summer, will see official U.S. release later this year. (No surprise, you can hear everything right now on the Internet.)

Ware’s delivery isn’t as muscular as Adele’s. It isn’t as overwrought, either. ­­Steeped in late-’80s R&B sensibilities — think Whitney Houston, Jody Watley, Pebbles — and gently pushing toward the future, her voice glows amid the detailed electronic timbres of right now. “It’s about combining them tastefully,” Ware says.

It’s also about proving that “tasteful” doesn’t have to mean conservative, predictable, nostalgic or any snoozy combination of the above. Her music results from an adulthood soaking up London’s nightclub futurism and a childhood singing along with Broadway musicals and classic jazz. “I think Frank Sinatra was one of the best,” Ware says. “He could phrase like nobody else.”

And while she doesn’t speak too highly of her own phrasing — “I think it’s crap!” — Ware undeniably knows how to breathe her syllables over a rhythm. You can hear it best on “Sweet Talk,” the EP’s most enchanting track. “I know I’m the weak one,” she confesses, but sounds anything but. Her hushed voice provides the song’s center of gravity while hi-hats click slightly out of time, keyboards throb slightly out of key.

It’s a welcome approach in an era when televised singing contests have conditioned us to think that great singing equals loud, blustery, roller-coaster melisma — a temptation that Ware knows well. “I don’t like over-singing,” she says, “but I used to love it. Oh, my God, I was so mad about it. All the trills.”

That was during her days touring the U.S. as a back-up vocalist for her buddy, London singer Jack Penate. On the road, Ware says she found her confidence behind the microphone. Now, she says she’s searching for that same courage in her songwriting, a process that daunts her, but, once underway, feels natural.

And isn’t that a lot like the love she’s trying to sing about anyway?

“Yeah, it’s like I had a really tricky love affair with songwriting,” Ware says. “People can be very scared of love, but once it starts . . .

She trails off, maybe dreaming of some prom somewhere.