Getting a session variable into Accounts.onCreateUser

[acomito]

Background:

• I collect information about a user's organization during my signup process.
• I want this organization information to be inserted as a document into a collection of "organizations".
• The schema for the organization includes the the user's id
• I take the organization data from the forms and store it in a session variable-- this all works fine.

I'm wondering where the best place/time to insert this organization document as I need the user's Id to have been generated? I suppose I can just use a method call but where should I call the method from?

further explanation here:
https://forums.meteor.com/t/best-practice-for-sign-up-insert-doc-to-additional-collection/22806

It seems many people need this:

• http://stackoverflow.com/questions/28955284/how-to-pass-info-from-client-to-oncreateuser-callback-in-meteor-with-accounts-ui
  -http://stackoverflow.com/questions/27272315/meteor-inserting-a-session-variable-value-into-a-field-upon-user-creation
• https://stackoverflow.com/questions/35026321/meteor-share-sessions-data-between-client-and-server