Over the centuries, ketchup has become a crucial component of the American diet. As the country gears up for cookout season this summer, it’s difficult to imagine a barbecue without the red, tomato-based condiment slathered on top of burgers, hotdogs, and French fries. The product has become so popular that Heinz, “America’s favorite ketchup,” sells roughly 650 million bottles of the sauce worldwide each year.

Still, despite ketchup’s all-American reputation, most would be surprised to learn the condiment’s fishy, foreign origins.

According to a new video from CNN’s Great Big Story, the first iteration of ketchup dates back to 6th century China, where the condiment was made using fermented fish guts and salt. For roughly a thousand years, the recipe called for fish bladder, stomach, and intestines to be left out in the summer sun for nearly three weeks, allowing the fermented concoction to reach a thick, paste-like consistency.  

The recipe might sound repulsive to us now, but back in the day the it was wildly popular throughout Southeast Asia, and beloved by European settlers. British and Dutch travelers were so infatuated with the condiment that they eventually brought the recipe back to their home countries, where ketchup received its first transformation. The British added ingredients like beer, walnuts, mushrooms, oysters, strawberries, and peaches into the mix, creating a sweeter, tangier sauce.

But by the time ketchup made its way in the U.S., the condiment was ready for its final evolution. James Mease, a horticulturalist and scientist from Philadelphia, created the sauce we know and love today, publishing his recipe in 1812.

“In 1804 he observed that ‘love apple’ — a popular term for tomatoes at the time — make for ‘a fine catsup,’” NPR noted in 2013.

Hundreds of variations on Mease’s tomato-based recipe followed, but it was Henry J. Heinz and the H.J. Heinz Company that popularized the spelling “ketchup,” ultimately turning the topping into the the national condiment of the U.S. By 2012, ketchup was found in 97 percent of American households

[via Great Big Story]