It's the first weekend since the rains cleared Portland's air of toxic smoke. The skies are a refreshing blue and the sun is yellow again.

At Birrieria La Plaza, though, one thing remains an unnatural red color: the tortillas. Each one has been dipped in chile-stained fat, before going on the sizzling comal with a generous mound of stewed beef and stringy white cheese to be served up as quesatacos.

The line to order stretches twice the length of the taco truck in deep Southeast Portland, nearly reaching the mariscos cart nearby, as masked customers wait dutifully at a proper social distance. Other cart owners in the Everyday Deals parking lot look on with envy.

Birria is having a moment. But unlike other darlings of Instagram's fooderati—rainbow bagels, pancake cereal—the birria boom is well deserved, built on centuries of tradition transformed into a trend by social media-savvy Mexican and Chicano millennials looking to satisfy cross-cultural cravings with crunchy tacos and birria ramen.

When most Mexicans and taco aficionados think of birria, they think of birria de chivo, goat marinated in a red chile sauce and slow roasted, traditionally underground or in clay ovens, as is found in Jalisco, Zacatecas, Michoacán and other parts of Western Mexico. The meat is succulent and tender, and creates a hearty broth called consomé that's served on the side and known for being a hangover cure.

With Oregon's many immigrants from Western Mexico, this style of birria has been served in Portland for decades. The familiar flavor and cheaper price of beef in the U.S., however, makes birria de res a great introduction to the style for unfamiliar Americans.

"I always liked birria since I was a kid, and now people are getting to know the dish," says Daniel Miranda, who works afternoons at Birrieria PDX after putting in a full day at his painting company. He cooks alongside his wife, Lorena, and sister, Grecya, who run the cart full time. "I think it's getting popular because it's beef instead of goat."

But birria de res, like its sibling, barbacoa de res, has a long tradition in many parts of Mexico. Birria de res is not a dumbed-down dish invented by shrewd bar owners to get gringos to chupa some chile and buy more cervezas, like nachos or queso dip.

"My family has always made beef birria, not chivo," says Oracio Hernandez, owner of Birrieria La Plaza, whose parents emigrated in the 1980s from a tiny mountain town in Jalisco. Cattle is what the people of his ancestral pueblito raised, so beef is what they used for birria. His recipe for the truck is his mother's.

But as birria made its way out of kitchens and into the streets of Tijuana and Los Angeles, it transformed. The main innovation was to add cheese—lots of it. Not a sprinkling of yellow American cheese or crumbly white Mexican cotija, but a handful of quesillo, Mexico's mozzarella, to melt into an oozing, gooey mess, crisping on the edges as it cooks on the comal, forming a taco called quesabirria or quesataco.

The second embellishment was not to just serve the consomé on the side or spoon a little into the tacos but to use it as sazón for the tortillas. L.A.'s most famous birria vendor named itself Teddy's Red Tacos for a reason: The tortillas soak up the fat and the broth from the birria, coloring them crimson. The tortillas are dipped in the red-stained fat before going on the griddle. Then, a ladle of burgundy broth is poured over the tacos as they cook, boosting the flavor and color of the tortilla and meat.

All the purveyors of quesabirria use this technique, resulting not only in stunning photos but delicious tacos that have customers returning even after they've 'grammed their pizza-sized platters of quesabirria. Taquerias and taco trucks that previously only served the standard asada, carnitas and pastor are adding quesabirria to their menus, attempting to capitalize on the trend.

Some, like Papi Chulo's in the Pearl, have served quesabirria and consomé since they opened, along with a more typical taqueria menu, making the eatery a popular late-night destination for hungry club and bar patrons before the pandemic.

Beyond quesabirria and quesatacos, birria de res specialists offer a variety of antojitos from the Sinaloa tradition by way of Tijuana, such as vampiros (tostadas with melted cheese and meat) and mulitas (two corn tortillas grilled with cheese and meat between them). Other inventive options include the keto taco, made with crispy melted cheese instead of a tortilla, and birria ramen, the Japanese noodle soup made with the broth of the birria, resulting in something that tastes more like pho or Thai boat noodles. Both of these dishes are on the menu at Birrieria PDX, but keto tacos are a special at La Plaza, while birria ramen is a special at Tacos El Patron in Aloha.

"My life has been around building the best taco," says owner Efrain Abarca, who takes the extra step of using corn tortillas made from freshly ground organic nixtamal. El Patron's birria doraditos, oversized corn tortillas wrapped around shredded beef and fried crisp, may be the best taquitos or flautas in the state (though they are only available on weekends).

Ultimately, however, all three birria de res specialists focus on quality, not gimmicks. Quesabirria may be trendy enough to attract the typical Taco Bell customer who pines for Doritos Locos, but it's traditional enough for Mexicans to drive across town for a bowl.

"We try to do everything with care and keep it authentic to the original recipe," says Hernandez. "We have people that tear up, and the biggest compliment is when people say it reminds them of the food when they were growing up in Mexico."

Where to Get It

Birria de Res Specialists

Birrieria La Plaza, 600 SE 146th Ave, Portland, tacoslaplaza.com. 10:30 am-7 pm Wednesday-Saturday, 10:30 am-5 pm Sunday.

Birrieria PDX, 16544 SE Division St., Portland, 971-336-6804. 11 am-9 pm Tuesday-Thursday, 9:30 am-9 pm Friday-Sunday.

Tacos El Patron, 21070 SW TV Highway, Beaverton, 503-372-6229. 11 am-9 pm Tuesday-Friday, 9:30 am-9 pm Saturday, 9:30 am-5 pm Sunday.

Birrieria Carlos, 9694 SE 82nd Ave, Portland, 503-810-1899. Call for current hours.

Other Taquerias Serving Quesabirria

La Tia Juana Taqueria, 18488 E Burnside St, Portland, 503-328-9691. 11 am-8 pm daily.

Papi Chulo's, 611 NW 13th Ave, Portland, 503-206-6085, papichulospdx.com. Noon-9 pm daily.

Sabor Casero, 5800 NE Martin Luther King Jr Blvd, Portland. 10 am-8 pm Monday-Thursday, 11 am-8 pm Friday-Saturday.

Traditional Birria de Chivo

Birrieria 7 Hermanos, 19131 E Burnside St, Portland, 503-916-9582. 10 am-6 pm Wednesday-Friday, 8 am-6 pm Saturday-Sunday.