Sending email out to all asset owners who's asset status is "pending return"

I want to create a Workflow that pull a list of assets with the status ‘pending return’ and the email the listed ‘used by’ on the asset.

the problem I’m running into is that ‘asset status’ is not something that can be filter by using a condition, but it can be filtered using the API and Web request. 

so I know have a string array with all the asset ID, I just don’t know how to use it since the all the action seem to require a string, and will not take a string array