A Chinese restaurant in San Francisco where Phlox and Hoshi Sato dined in 2154 just before the doctor was abducted on the street outside.
Madame Chang's is a restaurant in San Francisco on Earth, mentioned in the Enterprise episode Affliction.
With Enterprise back at Earth, Phlox and Hoshi Sato go there for a meal. Walking back afterwards through a quiet alley they are attacked by a group of aliens. Hoshi is knocked down and Phlox is carried off.
The kidnappers are Rigelians working for the Klingons, who need Phlox to find a cure for the augment virus. Hoshi's memory of the attack, drawn out with T'Pol's help through a mind meld, gives the crew their first lead.