Then there’s Korean-American Mercy (newcomer Ji-young Yoo), who was meant to be looking after the boy. And Hilary (Indian-American Sarayu Blue), Margaret’s neighbour, whose inability to conceive is wrecking her marriage.

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At the time the film’s success, which exceeded all her expectations, was hard to process. “I felt incredibly blessed and also a bit like, ‘Now what?’” admits Wang. But despite all the acclaim, she felt uncertain about taking on a bigger project.

“My goal is to have a body of work that I’m really proud of and I think the only way to do that, this early in my career, is to just keep working at a scale and a size where I can control the creative output.”

With that in mind, Wang initially passed on Expats, fearing she might lose her autonomy. “I love the book. I really love the book,” she says. “I just didn’t know how to direct one episode of a whole series. I didn’t know what the process would be.

“And so when I started talking to Nicole, I said, ‘I love the book, but this is how I see it, I think I would just have to make it like a movie, where I would direct all of them. I’m not sure how to do it any other way.’ And she was like, ‘Great. Let’s do that.’

“That was it. And I was like, ‘Oh, gosh, OK, well, I guess I can’t really say no now!’”

When we meet, 40-year-old Wang has come to the London Film Festival to present the fifth episode, “Central”, to audiences. The longest instalment by far – at 96 minutes – it also moves the story beyond the three core women.

An episode that widens the context beyond the central, well-heeled characters, it shows the perspectives of Essie and Puri, also non-locals but with no expat autonomy or civil rights.

“It was the first thing I pitched when I started talking to Nicole,” says Wang. “I said, ‘I’ll do the show but only if I can do this fifth episode, and I want it to work as a stand-alone,’” she says.

“I want people to be able to watch it on its own without the context of the rest of the show. But I also want it to fit as a part of the whole. It was really interesting to try to do both, right?”

“I didn’t really go to Hong Kong, I went to Shanghai a lot, and Beijing, and saw mostly mainland [China], but when I got older, I travelled to Hong Kong a few times just to spend time there.”

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Perhaps unexpectedly, it all left her confused about her own identity.

“I’ve been away for so long, and particularly when I go to Hong Kong, I’m an expat. An American expat. I’m definitely not a local. I don’t speak Cantonese. But I am Han Chinese, you know?

“So there’s a lot of overlap, culturally. It’s this weird feeling of, ‘What am I here?’ And that’s what I wanted to portray.”

After spending a year in Hong Kong researching, Wang decided the city was the perfect backdrop for what she wanted to say, “Because I think Hong Kong is this great microcosm of what our society is becoming more and more, which is that you can’t simplify people to an identity based on what you see and what they look like. Or even what language they speak.”

“People have just such complex identities because so many are leaving their home countries for various reasons. I just wanted to explore the people who live in diaspora around the globe.”

Not only was Wang inspired by Lee’s book, but also by her global press tour for The Farewell, which took her through Europe and out to Australia.

“So that’s what I thought could be a unique perspective to explore in Hong Kong.”

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Another reason Wang wanted to do the series was to show how much Hong Kong has evolved. “We felt a responsibility in capturing Hong Kong because it’s already changed so much. And it is continuing to change, to disappear.”

Unsurprisingly, Wang says she misses Hong Kong’s array of culinary experiences since returning to the US. Staying in Tai Hang, on Hong Kong Island, “we had a lot of favourite places”, she says.

“There were all these little yakitori places. It almost felt like Kyoto. And there was this restaurant called Mustard. It’s almost like a brasserie, and I would go there a lot because I knew the owner, who was a local.

“I was just astounded by the clientele. There was just something about it … I felt like, I don’t get to experience this in Los Angeles.”

“You can’t really go to Hong Kong without [experiencing that film],” says Wang. “That was my reference and my homage, I guess … a little nod to both Wong Kar-wai and Christopher Doyle.”

“Also, once we were there, we couldn’t leave. Nobody could leave, because then you’d have to do the quarantine again.”

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“In development, she was incredibly supportive in championing my voice and allowing me to write the script in a way that’s quite untraditional: it doesn’t follow a linear timeline, it delves into politics. So that was incredibly helpful, to have her support …

“Then once we’re in production, she really leans into just being an actor.”

As she told Vanity Fair recently: “The thing that was driving me was I knew that there was this political element that I felt so passionately about and that I wanted to portray.”

Whether Wang will return to television remains to be seen. “Maybe not for a while,” she says, “because I was working on this for over three years. And I don’t know that I’m going to have this kind of freedom always.

“I’m open to all experiences. Wherever I feel I can have the most creative freedom to do something unique and take a few risks, that’s where I’m gonna go.

“My next thing is a film for sure. I’m looking forward to something really nimble, being on set for a short period of time, editing, and then, boom! It’s done.”

Expats streams on Prime Video from January 26.