Process After Webhook Response

Hi,
I'm looking for advice on best practice to processing webhook data after returning 202 success to the webhook?
As there is only a short window for responding to the webhook (5 secs) and potentially a lot of heavy work to do processing the webhook data, I need to call a class or method in the controller AFTER responding to the webhook

Code:

return $this->response->setStatusCode(200);

Should this be done with a "post_system" Event (can I pass the webhook payload data to the event from the controller? can I restrict the event to being called only after a specific Controller has finished running?), or is there an alternative?
I would be grateful if someone could point me in the right direction?
Many Thanks