I feel like I'm missing something very obvious, all I need to do is return plain text (not JSON) in response to an action. If I use
returnJson() it returns the value with quotation marks around it. I'm dealing with a closed system that expects a VERY specific format, so the added quotations cause the submission to fail.
So for added clarification:
$returnValue = "abc,123" $this->returnJson($returnValue)