By that point, Wong, then in his 30s, was going through an identity crisis. He’d been in the United States for eight years, but he still felt like a ghost. His English was improving — he had read the Oxford English Dictionary cover to cover eight times — but to the ears of some Americans, he still spoke gibberish. He enjoyed chemical research, but he felt interchangeable with the next scientist. “I wanted to point to something and say, ‘That’s me,’ ” he said.

As Wong decided to keep telling jokes, the more he told, the better he got. Lizard Lounge, a tiny music club near Harvard Square, had a weekly stand-up contest — comedy at its most brutally meritocratic. Wong became a regular, testing out jokes at open mikes and culling the best ones for the competition. Finally, one week, he won. As he drove home through the snow that night, he was in shock. “I felt invincible,” he said. He went on to win five more times.

In 2003, Wong was one of 96 comics picked to participate in the Boston Comedy Festival, where he was spotted by Eddie Brill, the booker for “Late Show With David Letterman.” After several years of sending DVDs of his gradually improving act to Brill, he finally got the call to come to New York.

There was tension in the room when Wong first came onstage in April 2009. He didn’t look like a late-night comedian so much as a confused tourist who had accidentally wandered into the CBS studio. His khaki pants were pulled high, and his face read panic. “Hi, everybody,” he said, his voice straining. Letterman’s audience chuckled nervously. Wong let the silence hang. Then he said, “So, uh, I’m Irish.”

There was a wave of laughter, and then another wave as the absurdity of the statement sank in — an aftershock pattern that would become a Wong trademark. After that, he was flying. Every joke hit. The audience seemed to be laughing partly at the jokes themselves and partly at the unlikeliness of their vehicle. After seeing the routine, Louis C.K. praised Wong on his website: “Is this guy the best comedian in the country? No. But this set is very special.”

Wong soon had a manager, an agent and a lawyer. He started working with Letterman’s production company, Worldwide Pants, to develop a sitcom. He went on “Letterman” three more times and became a favorite on “The Ellen DeGeneres Show.” In 2010, he was invited to perform at the Radio and Television Correspondents’ Dinner in Washington. There, he addressed Vice President Joe Biden. “I actually read your autobiography, and today I see you,” he said. “I think the book is much better.”

After the correspondents’ dinner, Wong noticed he was getting more fan mail from China. The video of his performance had gone viral on the other side of the world, where viewers were marveling that a Chinese comedian had mocked the vice president of the United States to his face. Chinese journalists began contacting him for interviews. Those requests soon gave way to serious offers, including an invitation from CCTV to host a new weekly show in Beijing.