The piano was playing “I Left My Heart in San Francisco” the first time I walked into Hawthorn — all by itself, the keys sinking as if pressed by invisible hands.

That’s an image that won’t leave me when I think of this resolutely posh new restaurant tucked away on Upper Kirby, all dark velvet draperies and polished wood, with pale abstract canvases spotlit so that they glimmer in the sepia light.

If you’re thinking retro, you’re right: Hawthorn feels like a room out of Houston’s past. It’s the kind of place where oil grandees used to take their mistresses back in the booming 1970s. It’s dim and supper-clubby and discreet, a dreamy bit of time travel set to vintage piano music (which, on the weekends, is provided by an actual pianist who takes over from the auto-function, his laptop songbook shining before him, and whose eccentric pop repertoire ranges from Elton John to U2 to Lady Gaga).

But guess what? Despite the curious time-capsule vibe, Hawthorn’s food is mostly terrific. Read more: Why this place gets a three-star review