Salty, expensive and ultimately pretty polarizing, oysters are the old-school Hollywood divas of shellfish. These raw-bar prima donnas boast an almost-mythic quality, long a symbol of opulence and good taste—even virility. Few people know more about them than Julie Qiu, who’s made a business out of traveling the world on a quest to taste as many as possible.

After sampling countless different varieties from every major shellfish region in the world, she’s earned her stripes as a self-described oyster sommelier—a fitting title for Qiu, who says that raising the world’s best oyster isn’t all that different from crafting a world-class wine. Vintners and oyster farmers alike will subtly manipulate the look and feel of their yield by adjusting factors like aging and storage, but it’s the quality of the raw ingredients that will determine the overall taste of the product. “There’s not a lot of wiggle room around that,” Qiu says. “What you start out with is what you have to work with.”

Qiu herself is not an oyster farmer, just a determined enthusiast who managed to make a career out of aquaculture after years of running an amateur food blog and traveling the world doing market research for an oil company. It was during that period, circa 2008, that her love affair with the bivalves began to blossom (all the easier to develop expensive taste on an unlimited travel budget).

“I ended up going to eat oysters everywhere I could find,” Qiu says. In a little over a month, she had visited 18 cities on five continents, learning quickly that oysters have a more vast global reach than she would have guessed. “There are all these really interesting different pockets of people everywhere who love and are obsessed with oysters,” she says.

Back in the U.S., Qiu joined the nascent New York Oyster Lovers Meetup group, which deepened her relationship to the shellfish community. “I was thrown into this group of people who were actually in the seafood industry and who were able to connect me with a lot of resources and people around the world,” she says. “Now, I could visit farms and connect with a bunch of different people about the business of oysters—and not just at the raw bar.”

In the decade since, she’s continued her work in sustainable seafood, fine-tuning her expertise with speaking engagements and private oyster-shucking courses. But in all the different varieties and cultural customs that she has encountered in her travels, one thing remains constant: “Nobody has a neutral perspective about oysters,” Qiu says. “But they’re always a conversation starter.”

Below, she shares an insider’s look at her favorite oyster farms everywhere from Ireland to Hiroshima.