You can buy this in stores or on Amazon, but handmade is SO much better!
Wikipedia says that achiote paste is strongly associated with Mexican and Belizean cuisines, especially of Yucatán and Oaxaca. The paste is dissolved in either lemon juice, water, oil, or vinegar, used as a marinade or rub for meat, then grilled, baked, barbecued, or broiled. A similar condiment, called sazón (“seasoning”), is commonly used in the cuisine of Puerto Rico for meats and fish. It is made from annatto seeds ground with cumin, coriander seeds, garlic powder, and salt.
Achiote Paste
3 whole cloves
1/2 teaspoon allspice berries
Pinch nutmeg
1 bay leaf
¼ cup annatto seeds
1 tablespoon coriander seeds (or powder)
1 teaspoon cumin seeds (or powder)
2 teaspoons dried oregano
1 teaspoon black peppercorns (or chipotle pepper)
1 teaspoon kosher salt
5 garlic cloves, peeled
¼ cup distilled white vinegar
1 teaspoon finely grated lime zest
1 teaspoon finely grated orange zest
Blend cloves, bay leaf, annatto seeds, coriander seeds, cumin seeds, oregano, peppercorns, and salt in a blender on low speed, increasing to high, until finely ground.
Add garlic, vinegar, lime zest, and orange zest and continue blending until a coarse paste forms. Store in an airtight container in the refrigerator.