It's FINALLY been answered!!! The sauce was In-N-Out secret sauce:
http://www.buzzfeed.com/erinlarosa/good-burger-questions-answered-by-kel-mitchell#.vhqa2AEx7

The ingredients we know for sure that are in the sauce:
Malted Milk (ew) - that's the white powder he's sprinkling in
Pickles & Pickle juice
Red Pepper Flakes or a spice mixture that includes them
Whole onion(s)
Lemon Juice
Ketchup
Unconfirmed Ingredients (we never see them actually added or are told they're in there):
Mustard (on the workstation when he's making it)
Worcestershire sauce (bottle next to the pot)
Vinegar (in a little squirt bottle on the workstation)
"We are who we choose to be."

We know for sure it has ketchup and lemon juice. While making the sauce he adds pickles/pickle juice, corn starch (?) maybe, pepper I think, and whole onions. I always imagined it to be like the sauce In-n-Out uses on their burgers which is a thousand island dressing. Ed's is probably like that but more ketchupy.

It's a mix of ketchup and mayonnaiseand maybe some mustard.
At least, that's what it looked like to meand it really does taste good too.
Knawmean?!

"Ed's jizz"
LOL!!

Ed's jizz