Early Wednesday morning, 2 a.m. to be precise, Eric Greenspan issued a hamburger challenge to L.A.’s reigning hamburger king, Sang Yoon of Father’s Office. Greenspan, chef-owner of the Foundry on Melrose, staged what can only be called a covert food op, nailing his challenge — with ketchup — to the doors of the two Father’s Office locations, in Culver City and Santa Monica, under a thick cover of darkness and muffled hilarity.

The challenge isn’t personal (Greenspan says he’s never met Yoon) but professional. “Because he’s got the best burger, and if you want to be the best, you’ve got to challenge the best,” says Greenspan, who contends that his hamburger is as good if not better than Yoon’s celebrated burger and is willing to put it to the test — for local glory and a charity to be named.

The Father’s Office burger is a near-legendary construction, built from a burger (dry-aged beef), arugula, bacon, a combination of Gruyère and bleu cheeses, onion jam, and a French roll.

Greenspan’s take? A burger (80/20 beef, not aged), Cheddar cheese, oven-dried tomatoes, arugula, homemade mayo, tamarind-caramelized onions, bacon-pineapple relish and a King’s Hawaiian bread bun. The secret ingredient in Greenspan’s burger? Lard. “For extra juiciness; it seemed like the right thing to do.”

As for ketchup, the Foundry’s burger isn’t served with it, but the stuff is always on hand, whether for the burgers themselves or early-morning guerrilla events. Greenspan’s take on giving patrons what they want goes something like this: “If a customer wants well-done lamb, laugh at them, then give them well-done lamb; it’s a service industry.”

To issue the challenge, Greenspan and Foundry prep cook Josh McKnight headed out in a black Land Rover after closing the Foundry the night before, dressed in black, carrying posters printed for the occasion, with pantyhose (“Lace? Dude, you got lace pantyhose?”) over their heads and a squeeze bottle of ketchup — a condiment famously prohibited from Father’s Office. “We thought that it would be the best adhesive,” Greenspan says.

He and McKnight pinned the posters to the doors of each Father’s Office, scattered additional flyers in the respective doorways, then returned (“that was kind of Pythonesque”) to the Foundry. “I’m a man of the people,” says Greenspan, reiterating (sort of) that his challenge isn’t based on Yoon’s “near-Fascist approach to his burger,” but on its merits. As for other burgers worth fighting for, Greenspan says: “I wouldn’t even dare challenge In-N-Out. We’d have to drive to a lot of places; I’m not sure that we have the time.”

Jonathan Gold is on vacation. Squid Ink, the Weekly food blog, can be read regularly at https://blogs.laweekly.com/squidink.

The Foundry on Melrose, 7465 Melrose Ave., L.A. (323) 651-0915.

Father’s Office, 1018 Montana Ave., Santa Monica. 310) 393-2337; 3229 Helms Ave., L.A., (310) 736-2224.

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