From my experience, just dump a cup of canned or boxed beef stock in a small pot with a few slices of celery and carrot. Simmer for a few minutes, and strain it into a bowl with a spoon in it. No one really knows what aux jus is, just don't let them see you doing it. You can even do it the night before and have it ready in the fridge.
Edited to add: If anyone questions you, just hold up a dirty turkey baster and say "I pulled it off earlier."
Edited by Slow Drifter (12/27/17 07:01 PM)
"I have no idea what WW-III will be fought with, but WW-IV will be fought with sticks and stones."