The raw blood of ducks, geese, or pigs comprise tiết canh, a traditional Vietnamese dish known as blood soup. 

To make tiết canh, cooks first blend the blood with a saline mixture or diluted fish sauce to keep it from coagulating too quickly. Then they season the mixture, add baked or fried meat, and set it aside. Once the blood coagulates into a cool, silky pudding, it’s topped with basil, mint, or onion, and peanuts for an added crunch. Strong alcohol, usually rice wine, accompanies the final product. Tiết canh’s biggest fans rave about it, declaring it at once buttery and sour, with a gelatinous texture. Critics, however, describe a metallic taste.

The bright colors of blood soup give it a festive feel, which is why tiết canh often finds its way onto menus for celebrations such as the Lunar New Year and weddings. At the latter event, pigs are typically slaughtered at the host’s home. Outside of formal occasions, tiết canh makes for a protein-rich breakfast, sold in shops and markets. 

Popular belief holds that tiết canh has “cooling” properties that can regulate body heat and cure mouth ulcers. Many also believe that due to its key ingredient, blood soup might prevent anemia.

Given the risks of consuming raw blood, some health authorities are trying to stamp out the soup. While they haven’t been able to do so entirely, there are reports of declining interest among younger Vietnamese generations, possibly fueled by concerns over avian flu.