Begin by pouring the oil into a pan and warming it over low heat. Add the achiote powder, stirring to combine. Turn off the heat and allow the mixture to rest for 20 minutes.

Remove the shells from the shrimp and reserve them for the sauce later. Add these shells to the warm oil, letting them cook until they change color. Use a slotted spoon to carefully remove the shells from the oil.

Add the chopped onion and bell peppers to the pan. Cook for about 5-8 minutes, stirring until the onion is soft and translucent.

Stir in the minced garlic and cook for an additional minute.

Sprinkle in salt and oregano, stirring well. Next, add the shrimp and cook for two minutes on each side, just until they turn pink and opaque.

In a blender, combine the reserved shrimp shells and the coconut milk. Blend until smooth, then strain this mixture through a fine mesh strainer.

Pour the strained liquid into the pan with the shrimp and vegetables, stirring to combine.

Plate the shrimp mixture over a bed of cooked rice, garnishing with fresh parsley.