How to model mutual friends in MongoDB

We need to show mutual facebook friends for each listings (Similar to what airbnb does). We dont need to query by friends only show mutual connections for each listing. This would be relatively straightforward in a relational database, but I'm somewhat stuck on the best way to accomplish it in MongoDB. What is the best way to query for mutual friends between the logged in user and the listing owner? Should I query for each listing using a foreach loop individually after querying for listings or is there a way to query for both listings and mutual friends in one go?

The current schema that I have is:

Listing: {
   user_id: object id,
   ...
}

User: {
      _id: object id,
      friends: [{facebook_id: string, name: string}]
      ...
}