The first Chip Gaines heard of avocado toast was in 2017.

He and his wife, Joanna, were about to open a 200-seat restaurant in downtown Waco, Texas, where their home design and construction business is based. The family pancake recipe was locked in, and the biscuits and gravy were good to go by the time Mrs. Gaines mentioned adding a vegan option to the breakfast menu.

“That’s disgusting, babe,” Mr. Gaines told her, shaking his head. “No one wants avocado on their toast.”

She persisted. She also suggested a juice bar.

“I don’t like any juices,” he said, unhappily sampling some trial smoothies. “I like bacon.”

In the end, as fans of the couple’s popular home makeover show, “Fixer Upper,” will be unsurprised to hear, Mrs. Gaines prevailed. Magnolia Table opened with avocado toast on the menu, and has added chai latte and a $12 “juice flight” alongside basics like sweet tea and blueberry muffins.

In just seven years, since “Fixer Upper” began airing on HGTV, the couple has renovated more than a hundred houses and expanded the Magnolia brand into restaurants, craft markets, books, villas, real estate agencies, furniture, a magazine, a Target brand and — coming up shortly — their own cable channel, the Magnolia Network.

Their continuing negotiation between Texas tradition and modern taste makes for good television, and has also proved to be a wildly popular approach to home design, beloved by millions of followers on Pinterest and Instagram. In their hands, there is no house too small, too dark or too old to be transformed with topiaries (formerly known as houseplants), giant clocks, ironwork and white shiplap into her signature bright style, best described as Boho-Glam-Industrial Farmhouse.

That’s the aesthetic at the couple’s own home, a Victorian farmhouse set on 40 acres of land outside Waco that makes frequent appearances on the show. They live there with their five children, ages 1 to 15.

Part of the appeal of “Fixer Upper,” which drew more than 16 million viewers a week in its final season in 2018, is seeing that spark of tension play out in their marriage. In the tradition of Lucy and Ricky Ricardo and Homer and Marge Simpson, there’s one impulsive, enthusiastic risk-taker (Chip, 45) and one sensible, occasionally exasperated realist (Joanna, 42). And it takes both kinds to transform a business into an empire.

Mrs. Gaines has said that she started as a kind of “gofer” for her husband’s real estate business, Magnolia Homes. (He started flipping houses in Waco soon after graduating from Baylor University.) At first, she trawled antique markets and yard sales to decorate the houses that he was renovating; then taught herself digital design so they could completely rebuild older houses with the modern, bright interiors she favored.

Although their work seems to divide evenly, along conventional gender lines, it’s clear that her taste and vision (not to mention her snappy confidence and great hair) are the main drivers of the brand and its legions of female fans.

“They are a couple who respect tradition and one another, and aren’t afraid to show their Christian faith,” said Lindy Baker, a teacher who lives outside Kansas City, Mo. “She is proud of being a wife and mother, and you don’t always see that on the cooking shows.”

In a Zoom interview from home last month, Mrs. Gaines sounded like many parents who are currently working while attempting to be full-time educators, cheerleaders and cooks: frazzled.

“I had to get off social media for a while, so I made a full Texas dinner,” she said — chicken-fried steak, mashed potatoes and zucchini casserole. “It took three hours to make and it was gone in 10 minutes.”

Mrs. Gaines didn’t build her reputation on her home cooking, and when “Fixer Upper” premiered in 2013, she looked like no one’s idea of a Southern design queen, with her Birkenstock sandals, wardrobe of jeans and T-shirts and charcoal-gray manicure.

Her mother is Korean, and her father’s heritage is Lebanese: She slipped recipes for bulgogi and Lebanese salad into her first book alongside pimento cheese, chili and no less than eight breakfast casseroles. It has sold more than two million copies, and was the No. 2 best-selling cookbook in the United States on this week’s New York Times list — behind her new cookbook, published last month. (Her 2018 design book was also No. 1, and has a prescient title: “Homebody: A Guide to Creating Spaces You Never Want to Leave.”)

With no formal training or experience in design, decorating or cooking, Mrs. Gaines has felt her way into the domestic zeitgeist and become a star — and the first Asian-American woman to have a mass-market “lifestyle” brand.

“She’s like a Texas version of Martha Stewart and the Barefoot Contessa, but younger and more relatable” said Candace Fife, a superfan who started a Facebook group for cooks to post photos and notes on the Magnolia Table cookbooks. It has added nearly 1,000 members in the last two months, as home cooking has become a national necessity.

Ms. Fife, who lives in Houston and works at NASA developing suits for lunar travel, said Mrs. Gaines is the bridge between traditional Texas cooks, who have their own recipes for chicken spaghetti and banana pudding nailed down but always want to try out new versions, and “the younger generation,” (Ms. Fife is 64) who may never have made even the basics, like biscuits and mashed potatoes.

Ree Drummond, the Food Network’s “Pioneer Woman,” has some of the same fan base as Mrs. Gaines. Both women — Ms. Drummond in Pawhuska, Okla., and Mrs. Gaines in Waco — started out as “mommy bloggers,” and both used media skills acquired in college to stand out from the pack. Just as Ms. Drummond has made Pawhuska a destination with food and retail businesses, the Gaineses have done so on a much larger scale in Waco, where they have lived since graduating from Baylor University.

The Gaineses are often cited as a prime force in the revitalization of Waco’s downtown over the last decade, and (more rarely) criticized as serial gentrifiers who have made home prices and real estate taxes unaffordable for longtime locals.

They have been sued by the Environmental Protection Agency over lead-paint violations (and settled with the agency in 2018), and confronted about their affiliation with Antioch Community Church in Waco, whose pastor has preached against gay marriage and in favor of “converting” gay people to heterosexuality. (They have never stated their personal views on the matter, but their shows — unlike many other home makeover programs — have yet to feature a gay couple or family. A spokeswoman declined to comment, referring the Times to a blog post that Mr. Gaines wrote in 2017, after the election of President Trump, about building bridges between “people that don’t think alike.”

But locally, it is hard to argue with the revenue from thousands of Gaines fans who make the pilgrimage to Waco each year, or the benefits of the commercial projects they have brought to lots that were on the way to vacancy. Two giant cottonseed silos downtown were transformed into their first bakery and market; an expansion in progress will also house a church, a ballpark and multiple “lifestyle retail shops.” They currently employ about 500 employees in Waco, though some have been furloughed during the pandemic.

The Elite, once a popular stop for travelers between Austin and Dallas, was the oldest restaurant in Waco when it finally closed for lack of business in 2016; since the couple gutted and reopened it as Magnolia Table, two- to three-hour waits for weekend breakfasts are routine. Last fall, 50,000 people showed up for their annual Silobration festival (and shopping opportunity).

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Mrs. Gaines’ parents met in South Korea in 1969, when her father, Jerry, was serving in the United States Army. They married in Las Vegas in 1972 (to the displeasure of both families, she said), and settled in Wichita, Kan., where Mrs. Gaines spent most of her childhood.

There, she said, the teasing about her looks began; she was the only Asian-American child at most of the schools she attended. The family moved seven times for her father’s job with the Firestone Tire and Rubber Company; by the time Mrs. Gaines landed at Round Rock High School, outside Austin, she had developed such a phobia of school cafeterias that she was unable to eat in one.

“I barely knew what Korean food was,” she said. “But kids assumed that my food was different because I looked different.” (There is a happy ending to the high-school story: She moved to Waco in her junior year and wound up as homecoming queen.)

In fact, her mother, Nan, who was only 19 when she moved to the United States, didn’t know how to cook many Korean dishes, and briskly adapted to local conditions by developing a variety of ground-beef recipes like meat sauce and beef Stroganoff. Only when her grandmother arrived from South Korea to live with the family, she said, did Mrs. Gaines become familiar with homemade seaweed soup and bulgogi.

“The biggest fight I ever saw my parents have was about kimchi,” she said. (Her father wanted to move the pungently fermenting vegetables to the garage. Eventually, a second refrigerator was installed there.)

She explored mandoo and other Korean snacks during a college internship at CBS News in Manhattan. In New York, she said, she first had the experience of living around people who looked like her, and feeling that her Korean heritage was widely shared.

Still, what Mrs. Gaines really wanted to cook as a child was the cookies her friends’ mothers baked, and the fluffy pancakes served at Southern breakfast cafes — the kind of food her husband grew up on in Colleyville, near Dallas. You can sense that yearning to make those foods her own in her cookbooks, from the details in the recipes she worked on perfecting, like chocolate chip cookies and buttermilk biscuits. (Her personal, and extremely popular, formula for biscuits includes eggs and an overnight rising.)

There is not much that is aspirational about the food in her books, but much that is inspirational, especially in the photographs of Mrs. Gaines herself, of the children doing wholesome farm activities in muddy boots, of her cottage garden and white-tiled open kitchen. (In the “Fixer Upper” universe, and at their home, the kitchen is the domain of the lady of the house.)

Homely dishes like hash-brown casserole and peanut-butter brownies are presented against pure white and linen backdrops; some dishes are spilling over, or slightly over- or undercooked.

“It all looks very natural, like she does,” Ms. Fife, the superfan, said. “I think people relate because her food is not pretentious, it’s not for the elites, it just brings people together.”

Together, the couple made Time magazine’s list of 100 most influential Americans in 2019.

The Magnolia Network, whose roster includes food shows from the chefs Andrew Zimmern and Erin French, was originally set to replace the DIY Network on Discovery last October, but the debut has been pushed back indefinitely because production is stalled by the coronavirus epidemic.

“The way Joanna cooks is the opposite of what I do,” said Abner Ramirez, a singer-songwriter (and amateur pastry chef) who will cook on the new network. He and his wife, Amanda Sudano, perform as an acoustic duo, Johnnyswim; their track “Home” is the theme song for “Fixer Upper.”

Mr. Ramirez does what might be called “project baking,” challenging himself to make macarons, croissants, baguettes and other multistep recipes. “Everything she does is inviting, nothing is about showing off,” he said.

Both of Mrs. Gaines’s cookbooks are subtitled “A Collection of Recipes for Gathering,” and giant dining tables, open floor plans and family meals are a big part of the Magnolia brand.

Without the possibility of actual gatherings at the moment, she said, she is focusing on cooking from scratch and trying to enjoy the freedom to cook for hours instead of rushing to get dinner on the table after work.

It’s a good thing she has five children, she said. “It means we can still have a big family dinner, even under quarantine.”

Recipes: Sour Cream Chicken Enchiladas | Kale and Bacon Hash Brown Casserole | Peanut Butter Brownies

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