As I swallowed another spoonful of bird spit soup, I wondered, not for the first time, about what makes people prize one dish above all others.

Take this soup, for instance. Properly known as bird’s nest soup, it’s been a prized delicacy in China and among Chinese people for 1,200 years. The best nests were reserved as gifts for emperors and empresses, who ruled China as gods incarnate. That’s how deep bird’s nests roots go into the collective Chinese soul.

At some point, a cook was hungry enough to boil bird’s nests and have a swig. Maybe this particular brand was prized because it was devilishly hard to get. Tiny swiftlets use their sticky saliva to build nests onto seaside cliffs and cave walls, to save them from predators. That’s not enough to keep them away from the humans who consider the nest powerful medicine, and are therefore willing to pay more for the bird spit nests, pound for pound, than silver.

So there I was at a table inside Sun Restaurant Buffalo, 1989 Niagara St., feeling downright unappreciative, unworthy almost, of this spoonful of bird spit. Across the table, proprietor Kevin Lin explained he was selling bird’s nest soup for $40 a bowl.

That’s zero profit, he said. “I want to have it because I come from bird’s nest region,” Lin said. “Because it’s a good thing, so good for you, and we want to let people get good things, like us.”

I could only nod, because the most expensive ingredient sold in a Buffalo restaurant tastes like nothing. I said so to Lin, and he shook his head. I wasn’t getting the point. “You want flavor? I recommend tom yum soup. Five dollars.”

The jellylike strands had a slippery spaghetti texture, yet no discernible taste beyond sweetness from the rock sugar the meticulously cleaned nests were steamed with. It occurred to me that here was a food whose value had nothing to do with its flavors or eating qualities, and everything to with its cultural history. Or in Hollywood terms, the backstory.

While trade in edible nests has been recorded since the T’ang Dynasty (618-907 A.D.), famed 15th century Chinese admiral Zheng He is also credited with starting the Chinese belief in the medicinal powers of bird’s nest. As the story goes, shipwrecked sailors scavenging for food found the nests, and He told them to clean and cook them. A few days later, the sailors were full of vim and vigor, and He figured he should tell the emperor.

The rest, as they say, is legend. The fact that they were cleaned, dried strips of bird saliva didn’t stop yan wo, literally “swallow’s nest,” from becoming one of the most prized tonics in traditional Chinese medicine. The nests have been credited with a long list of benefits, including ensuring strong children for pregnant women and erasing wrinkles for mature matrons, providing lifelong immunity boosts for children and enhancing sexual prowess for men.

Which is why the nests have been harvested across China, Malaysia and other coastal Asian regions as long as the Chinese have been buying them. Teams of gatherers scale bamboo ladders and dangle from ropes to get at the nests. It’s the biggest cash crop for some villages.

If they’re careful, gatherers take nests no more than twice in an egg-laying season, or the birds can’t rebuild in time. There have been documented cases of overharvesting driving off swiftlet colonies. But the hardy little bird has confounded man’s hunger for centuries, and is not listed as endangered.

Recognizing their value, Thai, Burmese and Indonesian entrepreneurs have been building condos for edible nest swiftlets, purpose-built structures as tall as apartment buildings. They’re honeycombed with alcoves where swifts can nest, lured by recorded swiftlet calls broadcast over loudspeakers.

The Lins’ story starts with Stephanie, Kevin’s wife. She’s Burmese too, but her father was ethnic Chinese, and started feeding her bird’s nest soup when she was 2. He could afford it, because he owned a pineapple canning factory and was rich, by Burmese standards.

The Burmese have no particular affinity for bird’s nest soup, Kevin Lin explained. The Burmese government controlled the nests’ collection and export, as a precious commodity. But Stephanie’s mother got the nests from a black market source, and made soup the traditional way, steaming the nests with rock sugar.

“Stephanie’s father would wake her up at 2:30 [a.m.] to drink bird’s nest,” Kevin Lin said. The nest’s medicinal qualities are best absorbed on an empty stomach, fans say. She got it perhaps four times a year, and believes it helps keep her healthy today. Her husband’s a believer, too. “I am a healthy man, but her family, her older sister never get sick. So I suspect bird’s nest.”

Despite the lack of Chinese background, Kevin knows about bird’s nests. At 21, before he met Stephanie, he was a bird’s nest smuggler, he said. He’d buy them in Burma and sell them in Thailand for twice the price, he said.

“Whole time I sell it I never eat one piece,” said Lin. “Too expensive.”

The first time he drank it was on his wedding day with Stephanie, in 1997. His mother-in-law fed it to him. Asked if its effects were felt that night, he just chuckled.

In December, Lin returned from a trip to Burma with a bag of bird’s nests, determined to put it on the menu.

So that’s why his menu now includes traditional bird’s nest, $40, steamed with rock sugar; in chicken soup with ginseng, another honored Chinese medicine, $50; and bird’s nest over a scoop of vanilla ice cream.

“I invent this one,” Lin said. “This is Western bird nest. Like cake.”

At home, the Lin boys are getting their dose too.

They were a little wary at first, but the rock sugar won them over, Stephanie said.

“Now every morning they want it,” she said. “Mom! Bird’s nest!”