In a spice grinder or food processor add the ground coriander, cumin, achiote, oregano, cilantro, garlic and onion powders, kosher salt and pepper and pulse until a fine grind. Store in an airtight container.
Notes
If Annatto seeds or achiote powder is not available, you can substitute with a good pinch of saffron threads or same amount of turmeric. If saffron is unavailable or not to your liking, another substitute is to combine 1 part turmeric to 2 parts paprika.
For Latin cooking, I prefer to use Mexican oregano, but feel free to use regular oregano.
This makes about 1/2 cup total or 24 teaspoon servings.