Also known as steamed buns or baozi (包子), bao is a complete meal conveniently packed away in a white, warm, soft bun.

Filled most traditionally with a pork mixture, the perfect bao should be round, smooth and soft. And it should be steamed in bamboo baskets, giving off a subtle woody scent, says Tom Tong, founder of Tom’s Bao Bao, a steamed-bun-focused restaurant with more than 200 locations in China.

Tom’s Bao Bao will make its U.S. debut today in Boston’s Harvard Square. The chain’s first American outpost will serve a pork bun, curry beef bun, chicken bun, sweet potato bun, vegetarian bun and a seasonal lobster bun.

Tong says achieving the highest quality bun requires very exact practices performed by dedicated bao artists whom he calls “baoists.”

“It’s a very long and complicated process,” Tong says through a translator. “From mixing the dough from scratch, all the way to the steaming, it needs to be a continuous process; there’s no room for pausing. Our baoists have to be not too fast, not too slow. There’s a very exacting pace in this process. We can’t even let the dough rest too long in the palm of their hand for fear of warming the dough, which will overproof it.”

Tong grew up eating the bao and even remembers his first hot bun. “When I was about seven years old, I remember my grandfather taking me to a farmers’ market, and he bought me a bao as a treat,” he says. “It was a pork bun, and it was very soft and juicy. I can still recall the hint of scallions.”

Check out the gallery below to see how bao is made.