Mandu could have been mistaken for a hot nightclub with a line of people camped out down the block at 10 p.m. on a recent Friday night. But instead of a bouncer, a host ushered in the crowds. Within 10 minutes, every seat in the Korean restaurant was full, with people two or three deep shouting orders at the bar. In the house that night? Guest chef Katsuya Fukushima of Daikaya. Sure, all these people could walk just a few blocks south to try his cooking any day of the year. But for one night at Mandu, he teamed with chef Danny Lee, Lee’s mom Yesoon Lee, and Jonah Kim (formerly chef of Baltimore’s Pabu) for Anju, a monthly pop-up serving Korean-inspired drinking snacks. Rather than cooking their normal hits, the chefs experimented with things that might otherwise be too wacky for their menus: ramen quesadillas, mapo tofu frito pies, and kimchi bolognese.

Every month, a different chef takes over the kitchen at Mandu for the late-night party. But Lee never intended for Anju to be this way. When Lee and Kim, his good friend, launched the pop-up in June, it was just supposed to be them in the kitchen. The original goal was to gauge interest in dishes for a possible late-night Korean bar snacks restaurant that Lee would like to open. But among the crowd at that first event were fellow chefs—like Vermillion’s William Morris and The Source’s Scott Drewno—and when things got busy, they jumped in the kitchen to help push out dishes. That sparked the idea: Why not bring in different guest chefs every month?

Anju is just one of the many guest chef series and collaborative pop-ups or “takeovers” proliferating in D.C. these days. Whereas many chefs were once very possessive of their own territory, now they seem to be playing a game of musical kitchens. It’s no longer weird to find someone cooking Chinese food in an Italian restaurant one night or a French chef taking over a Korean kitchen another. The result is not only some interesting mash-ups, but it could be paving the way for potential collaboration restaurants down the line.

Among the first and most prominent recurring guest chef series is Mike Isabella’s Industry Takeover Nights at Graffiato. On the first Monday of every month, Isabella invites a rotating roster of chefs and bartenders from around town and the country to take over his first-floor pizza bar. Isabella was inspired to start the events after doing a cookbook signing at Amis in Philadelphia, where chef Marc Vetri hosts his own monthly industry nights. In Philly, people have to show a restaurant pay stub to get into Amis’ industry meal. “It was to kind of give back to all the cooks and people like us,” Isabella says. “I thought that was a good idea.” Isabella put his own spin on it by opening industry night to everyone and giving outside chefs free rein in his kitchen rather than doing the cooking himself. At first, the always-packed events brought in local chefs and a couple of Isabella’s Top Chef co-stars, but now, chefs from as far away as Seattle, Louisville, and Miami are folded into the line-up.

In the past, a visit from a guest chef was a far more formal affair; out-of-town toques might make a special visit to present a tasting menu or something equally official. “Now, it’s a thing that people build into a regular part of their business,” says Tiffany MacIsaac, former pastry chef for Neighborhood Restaurant Group and founder of the in-progress Buttercream Bakeshop. She’s been a guest chef at both Mandu and Graffiato. “Before, it would be a much bigger deal if a chef came to cook in your kitchen.”

MacIsaac says the popularity of Industry Takeover Nights at Graffiato has been a catalyst for other similar events. But even before restaurants started hosting guest chef nights, chefs would crash each other’s kitchens at the end of their shifts for some late-night grub. “We’d be hanging out at someone’s restaurant, and someone would just end up cooking something if they got hungry,” Lee says. “Mandu is definitely one of the places where a lot of people used to hang out.”

That’s also how Boundary Road kick-started its Sunday night guest chef series, which takes place weekly throughout August and September and may continue monthly after that. Chef Brad Walker says his restaurant has become a hangout for a lot of industry folks on H Street NE. “A lot of times, we’ll all be hanging out talking about what we’re cooking or, ‘Hey, if I were here, I’d be doing this,’” he says. “It was born out of that.”

In that way, these events are another door for the public to access chef life. “People are more into the inside culture of restaurants,” Walker says. Chefs were already hanging out and cooking food late-night. “And now we’re just taking that to a level where people can come and experience what it’s like.”

Guest chefs don’t get paid to cook at events for Boundary Road, Graffiato, or Mandu. Isabella, however, will pay for out-of-town chefs’ travel and accommodations and give them free meals at his restaurants. In most cases, the host restaurants will procure any ingredients the chefs need, although at Graffiato, many chefs tend to bring food prepped from their own kitchens. And they don’t skimp: At the last Industry Takeover Night, former Bourbon Steak chef David Varley, now at RN74 in Seattle, flew in geoduck, a large, pricey clam native to the Pacific Northwest.

Industry Takeover Night isn’t much of a moneymaker for Isabella, either. In fact, sometimes, he loses money on it. Half of the $10 cover charge goes to a charity of his or the guest chef’s choice, and the rest typically goes to hosting the chefs. The events do, however, have some marketing value. Isabella says they bring in customers who’ve never been to his restaurants before, and it helps build business for the visiting chefs, too. “When people go to these cities, they know some of these chefs now,” he says. But hosts like Isabella will tell you marketing isn’t the main drive behind these events. Rather, it’s an excuse for chefs to just hang out, learn from their peers, and of course, party.

They may not get paid, but plenty of restaurant people are clamoring to participate. While many of the guest chefs are friends of the hosts, Isabella says he now has people contact him from around the country looking to participate. Meanwhile, Lee made a list of people he’d be interested in having, and his publicist helped extend the invitation to some chefs. “Everyone said yes,” he says. “It’s very humbling for my mom and I. All these incredibly talented chefs want to sacrifice their Friday night, come in, sweat, work pretty hard at our restaurant without getting paid for it. It is a straight 100 percent passion decision.”

Since there’s not much of a late-night dining scene in the District, MacIsaac says, these events fill a niche. Plus, it gives chefs an excuse to get out of their comfort zones. “When you’re in a restaurant, you’re kind of in a bubble,” MacIsaac says. “It’s like being in a soap opera—everything is so intense and you’re just in it. So it’s really nice to step out of it for a minute and go and be in someone else’s bubble and see what they’re doing and get reinvigorated and re-inspired.” For example, after preparing for her stint at Mandu’s Anju pop-up, MacIsaac decided to try her hand at kimchi for the first time, and Lee walked her through it.

“You always learn something,” Lee says. “You see some piece of equipment that you haven’t used, or you see them using something in a different way… The only way you can get better in this industry is by seeing different things, and the best way to do that is to visit another person’s kitchen.”

Isabella believes the next frontier will be collaboration restaurants, where chefs aren’t just cooking with each other for a night but actually opening businesses together. “Do I want to go to one restaurant, or do I want to go to a collaboration restaurant where it’s going to be totally different and totally unique and actually two different people’s food in one concept?” Isabella asks. “That’s where I think the industry will slowly go as people get bigger, and bigger, and bigger, and try to do different things.”

Partnerships like this are starting to happen. Mixologist Gina Chersevani teamed up with chef Jamie Leeds to open Hank’s Oyster Bar on the Hill, and Shaw’s Eat the Rich is a joint venture between Rappahannock Oyster Bar owner Travis Croxton and The Passenger owner Derek Brown. Meanwhile, Toki Underground chef Erik Bruner-Yang is working with Will Sharp, the founder of D.C.-based men’s sportswear/streetwear brand DURKL, to open a hybrid food and fashion market on H Street NE. But so far, D.C. hasn’t really seen two chefs partner up to open a restaurant that brings together their unique styles.

Isabella demurs when asked if he personally has such plans. “I don’t know,” he teases. “There are chefs that I would like to partner up with down the road… I think it’d be cool to pair up with some type of chef that does Asian food or team up with a guy who’s a Southerner who does barbecue…It brings something unique and different when you put different styles together.”

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Photo of Mandu chef Danny Lee by Darrow Montgomery