Create Asana tasks to handle code reviews in Differential.
Phabricator is a collection of open source web applications that help software companies build better software.
Login to Phabricator as an administrator and add Asana as an authentication provider in the Auth application (this has on-screen instructions).
Configure 'asana.workspace-id' using the Config application (this will walk you through the process, too).
Restart the daemons (phd stop; phd start) to have them pick up the config change.
Have users link their Phabricator accounts to their Asana accounts in Settings -> External Accounts. Once the link is established for a user, integration will automatically activate.