Dissolve the achiote paste with the vinegar and orange juice, then set aside.

Heat 1 tablespoon of oil in a skillet. Add the pork, cut into cubes, and cook for 8 minutes.

Season with salt and pepper, then add the achiote mixture.

After one minute, add the pineapple pieces and cook over low heat for 10 minutes, or until the pork is cooked through.

Serve in tacos with your choice of vegetables and salsas.