As El'endia commented there is currently only one candidate for this right now and it's not a good choice. It really doesn't show off what answers should look like on this site. Most notably the answers that would show up are not explicitly scoped to match the question. As that's the one point new users have the hardest time coming to grips with I think it's essential that we highlight it on any example posts.
At this point the only idea I have is to contrive an example by composing it here on meta with community consensus, then posting it on main, getting it the votes it needs to qualify, then locking it so it doesn't get messed up. To this end I would suggest finding some good existing Q&A that is really representative of the site and edit it down to a short summary of its initial self.
Edit: The Unicorns are gone! Please feel free to still chip in here if there are any further suggestions for refining this.