"Our shengjian are among the most popular — there's a long line every day during lunch time," said Wei, who came from Central China's Henan province to Shanghai in 2010, and learned to become a Shanghai dim sum chef.

"I was told to make the best shengjian for our guests, and I hope they'll like it," he said.

Wei can't speak English, but he said some foreigners gave him a thumbs up after eating the buns.

Wei and his wife both work for Dahuchun in Shanghai. The restaurant provides accommodation and a base pay of more than 3,000 yuan per month.

They have a 6-year-old son in their hometown Xinyang in Henan, but Wei hasn't had the chance to bring him to Shanghai.

"We usually go back to see him during the National Day holiday in October," Wei said. "Maybe next year I will take him to Shanghai to see the expo."