Annatto seeds, also called achiote, are the small reddish-orange seeds of the Bixa orellana tree, native to tropical Central and South America. They have been used since pre-Columbian times as a natural food coloring and mild flavoring agent, and are the raw form from which annatto oil, paste, and powder are made.
The seeds are usually infused in oil, vinegar, or another liquid to release their pigment (bixin and norbixin), since eaten whole their flavor is subtle: mildly nutty, slightly peppery, and faintly bitter. Annatto seed is a staple of Latin American and Caribbean cooking, used in achiote-marinated meats, rice and beans, and various stews, and of Filipino cooking (as atsuete), where it colors adobo and other dishes.
Like saffron and turmeric, annatto seed is used to color food yellow to orange, but it has the mildest flavor and lowest cost of the three.