Kim Richards -- The Post-Rehab Chow Down

With a big smile on her face, "Real Housewives of Beverly Hills" star Kim Richards hit up Mr. Chow last night ... her first public outing since checking out of rehab earlier this month.

The 47-year-old went to the Beverly Hills celebrity hot spot with her big sister Kathy Hilton.

In December, Kim entered rehab for treatment of alcohol abuse and other "serious issues."

Family members have said Kim is doing "really well" since completing the 30-day program and are optimistic she'll stay on track.