I hadn’t heard of butterfly pea flowers until we moved to Thailand, where drinks come in a range of bright colors. Beverage menus here often look like rainbows, from brick-red Thai iced teas to verdant milky-green matchas.
However, the most vivid drink on anyone’s table is an electric blue or lurid purple. The key ingredient is butterfly pea flower, or Clitoria ternatea—sometimes just known as “blue tea” or, strangely, Asian pigeonwings. The flowers have virtually no taste; when sold as tea, the dried flowers are typically packaged with dried lemongrass to add flavor, then you might add honey or even passion fruit to the drink.
Inevitably, bartenders also use the teas for flashy cocktails. This can involve a show, since the tea has an unusual property: Originally a bright blue, the drink turns purple once you add an acid, such as a squeeze of lime juice.