sideband call to external URL

I think Aaron's is one of the better examples of a sideband call:

https://devcentral.f5.com/codeshare?sid=686

Notice in his example that he's defining the virtual server to send the request:

set static::sb_vserver "sideband_dest_vs"

It is always-always-always (did I mention always) a best practice to target a virtual server versus contacting a remote server directly. Not to mention sideband calls don't directly support HTTPS/SSL requests. Your remote server is defined in the pool of this internal port 80 HTTP virtual server, with a server SSL profile applied as required.

You're going to get the response back in the recv_data variable, which is going to be the raw HTTP payload. Now, should you need to make a cookie from that data, keep in mind you'll either have to do that in a response flow to the client, or completely preempt the server side flow with an HTTP redirect or respond.