In a small saucepan bring water and achiote seeds to a boil.
Cook seeds, covered, at a bare simmer 30 minutes and remove from heat.
(Steep seeds 2 hours, or until softened.) Heat a dry comal or flat iron griddle over moderately low heat until hot and pan-roast garlic and onion, turning them occasionally to ensure even roasting, until browned and soft throughout, 25 to 30 minutes.
Discard garlic skins.
In a small heavy skillet dry-roast oregano over moderate heat, shaking skillet occasionally, until fragrant and beginning to brown, about 2 minutes and transfer to a small bowl.
Cool oregano completely and in an electric coffee/spice grinder grind fine.
Drain seeds and in a blender or food processor blend with garlic, onion, oregano, and remaining ingredients until smooth.
Recado may be made 5 days ahead and chilled and covered.