At first glance it looks like a couple tucking into In-N-Out but when you take a closer glance you can see that something isn't quite right.

Food influencer Grace Lewis, 48, who goes by Crazy Korean Cooking online and has 2.1 million TikTok followers, was looking for a project for her next video, so decided to replicate the West Coast-famous burger chain in New Jersey so her parents could try it for the first time.

'Let's do something quick, you know, something quick and fun, whatever,' Lewis told the Daily Mail about how the idea began.

'I was like: "You know what, why don't we try to do like In-N-Out? It's on the West Coast, people love it, everyone loves it, it would be nice to take mom and dad there. Obviously, we don't have it, but it would be really interesting to try to make it at home.'"

Grace and her sister began researching In-N-Out's recipes, ingredient lists and old promotional videos, but quickly realized recreating the famous burger chain would require far more than buying buns and burgers from the grocery store.

Instead, they made nearly everything themselves, including the American cheese, ketchup, mustard, relish, pickles and burger buns, while also recreating the chain's branding, uniforms and drive-thru experience.

'It sounds easy, it's a burger,' said Lewis, who called her fast food joint Out-N-In. 'But once we started, it quickly turned into something much bigger than we expected.'

Lewis said she and her sister tend to build on each other's ideas, expanding the project step by step - from recreating the packaging to transforming a spare window beside their driveway into a functioning drive-thru.

The deeper they researched, the more they discovered that In-N-Out's ingredients weren't quite as ordinary as they expected. 

The chain's ketchup doesn't contain corn syrup, its pickles are flavored with garlic oil rather than dill and even its burger buns follow a distinctive slow-rise process.

'We went through all the ingredient list and some old promotional videos that introduce their production process and some history,' Lewis told the Daily Mail.

She said she made the buns six times to get them perfect, despite being gluten-free.

The bread ultimately proved to be the hardest part of the project. Lewis said baking was far less forgiving than cooking because mistakes couldn't be fixed halfway through, forcing her to start over until she got the texture just right.

Because she couldn't properly taste the buns herself, she relied on her sister - the only member of the family who had actually eaten at In-N-Out - to decide when they were finally close enough to the real thing.

Another discovery during their research helped shape the finished project.

'During our research, I found out that they were the first ones to adapt the speaker system for the drive-thru,' Lewis said.

Inspired by that history, the sisters transformed a spare window beside the family's driveway into a makeshift ordering station, complete with a menu board and speaker.

The recreation held special meaning because Lewis' parents moved to the United States from South Korea about five years ago and had never tried In-N-Out. 

Because they weren't comfortable ordering through a speaker in English, Lewis said they also had never placed a drive-thru order on their own.

When everything was finally ready, her parents pulled into the driveway and ordered just as they would at a real In-N-Out.

Her mother, 70, chose a Double-Double animal style, while her father, 76, ordered a 4x4 animal style, along with animal-style fries, a shake and a Lemon-Up.

'They really loved it,' Lewis said.

For Lewis, seeing them comfortably place their first drive-thru order was just as rewarding as finally serving them the famous burgers.

Everyone's favorite part of the meal was the sauce.

'The sauce was really good,' she said. 'The fries, oh my god! The fries with the sauce, with the onion – caramelized onion – it was so good.'

Lewis joked that perhaps the biggest irony of the entire project was spending nearly a week painstakingly recreating a meal designed to be served in minutes.

'It's fun as a concept because it's not something people do,' she said. 'You're making fast food at home - but in the slowest way possible.'

In-N-Out was founded in 1948 and is headquartered in Irvine, California. It has more than 400 stores but famously does not have any outlets on the East Coast.

It does not franchise and refuses to use frozen beef. Its closest location to the East Coast is Nashville, Tennessee.