After testing the restaurant out with her friends earlier in the year, the actress brought her boyfriend, producer Brad Falchuk, for an intimate dinner at her favorite tempura spot, Tempura Endo, on Monday night.
"Gwyneth had a girls' night at the restaurant earlier this year and loved it," a source tells PEOPLE of the Beverly Hills restaurant.
"She booked a private table for a few friends to celebrate Brad's birthday," the source adds. "It was just a small, casual celebration."
The 43-year-old actress dressed casually in a long-sleeve black blouse, green skirt and slip-on shoes.
For dinner, they ordered several Kyoto-style tempura dishes, including tempura bowls. The party also sampled tea from the restaurant's tea ceremony room.
"Gwyneth looked beautiful," the source notes. "She is always very friendly and had fun with Brad. They looked very happy."
The couple recently wrapped up a string of romantic winter getaways, which took them to Mexico, Austria and Paris.
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Meanwhile, Paltrow's split from Chris Martin hit a minor speed bump this week, when a judge brought to light the fact that Martin has yet to file a response to his ex-wife's 2015 petition for divorce.
According to court documents obtained by PEOPLE, the actress may now be eligible for a default judgment, which normally means she'd be entitled to everything she asked for in her original petition.
Martin has 60 days to respond, although it is unlikely his late filing will have any repercussions on the couple's settlements.