Shack Sauce

I would argue that Shake Shack's Shack Sauce is almost as important on a Shack Burger as the patty itself—it's what differentiates the Shack Burger from Shake Shack's regular cheeseburger. It's by all accounts a "secret" recipe that was going to take a bit of hard-core investigative journalism to uncover.

My first attempt was to play the Shack-virgin card. When I got to the front of the line at the Upper West Side location one Monday afternoon, I innocently asked the cashier, "So, what's the Shack Sauce?"

Her response: "It's mayo-based. Sweet, sour, hot."

I went fishing: "How spicy is it? Like it's got hot sauce in it or something?"

But she didn't take the bait: "A little spicy. But also sweet and sour."

One last try: "So, sweet like thousand Island? Like it's got relish in it?"

She's an inscrutable blank wall: "No, no relish. Mayo-based, sweet, sour, hot."

I give in: "Okay, give me a Shack Burger, extra Shack Sauce on the side."

Upon tasting it, my immediate thoughts are mayo, ketchup, a little yellow mustard, a hint of garlic and paprika, perhaps a touch of cayenne pepper, and an elusive sour quality that I can't quite pinpoint. It's definitely not just vinegar or lemon juice, nor does it have the cloying sweetness of relish. Pickle juice? Cornichon? Some other type of vinegar? I can't figure it out. This was going to take a little more effort.

My next strategy was a little more drastic: "accidentally" walking through the hidden door in the downstairs rec-room that leads to the kitchen in the hopes of taking a sneaky glance at their pantry for hints. No good. I got halfway through the door, only catching a glimpse of a few cans lining the right-hand wall before it was pointed out to me by a friendly employee that the restrooms were actually behind the doors clearly labeled "restroom."

I sat on the bench outside contemplating a bit of dumpster diving when a thought struck me: Maybe I was going about this all wrong.

I walked back into the restaurant, went straight up to the manager, and asked point blank: "Is the Shack Sauce a secret, or can you tell me what's in it?"

A little laugh, and then, "It's mostly mayo, with some ketchup, mustard, a few spices, and pickles blended in."

"So, pickle relish, or pickles?"

"Actual pickles—the sliced pickles we serve with the burgers. I couldn't give you exact tablespoon measure or anything because I don't know them off hand, but that's the general idea."

Note to self: Always ask nicely before moving on to breaking-and-entering.

The rest was easy: I brought the extra sauce home, then tinkered around with a blender and my spice rack until I got a pretty damn-close approximation. Can you pick out which is the real sauce in the pic above?

As for applying the sauce, the key here is generous, even coverage. For the sake of absolute authenticity, I transferred the sauce to a squeeze bottle, and squeezed out three lines onto the top half of the bun, going back and forth three times along each line.