Pasta de Axchiote is a paste made from Annatto seeds that have been ground up. It gives a dark red colour to food, but no additional taste.
You can use it as is in your cooking, stirring some of the powder into the liquid of what you are cooking, or rubbing it into the surface of meats.
If you crush the seed yourself, don’t use a mortar and pestle that you are fond of, as they may get stained a dark red.
If you use a coffee or spice mill, make sure all the parts that it will come into contact with are washable.
“Achiote” is another word for “Annatto”. “Pasta” means “paste”.