Demi Moore in Mexico on January 10, 2013. Credit: XPOSUREPHOTOS.COM

Is it 2013 or 2003? Demi Moore, 50, showed off her bikini body during a private getaway in Tulum, Mexico on Jan. 2 -- looking nearly as trim and taut as she did ten years ago, when she unveiled her figure in a two-piece during an iconic beach scene in Charlie's Angels: Full Throttle.

Wearing a super-skimpy Missoni bikini, the LOL actress was spotted emerging from the surf at the Amansala Eco-Chic Resort alongside a shirtless, hunky mystery man on Jan. 2. (Earlier photos from the excursion revealed Moore sitting in the sand among other women for a surfside "boot camp" -- covered with clay from a spa treatment.) During the solo vacation, Moore also indulged in massages, yoga classes and other spa treatments.

The next week, Moore was photographed back on home turf in Beverly Hills -- dining with restauranteur (and Lindsay Lohan ex) Harry Morton, 31. But despite speculation to the contrary, a source close to Moore tells Us "they are absolutely not dating."

Meanwhile, Moore future ex-husband Ashton Kutcher -- he filed for divorce in December, over a year after the couple announced their separation -- is getting decidedly serious with love Mila Kunis.

"Ashton wants to move on with his life," another insider tells Us.