Rub 1 tbsp of cumin, 1 tbsp of garlic salt, and 1 tsp coffee over roast, and let sit at room temperature for 15 minutes.
Meanwhile, add 1/2 cup of oil to the achiote seed in a small saucepan and cook over medium heat for 5 minutes or until the oil is red and fragrant. Be careful not to let the oil burn. Strain 1/4 cup of oil into a large, heavy-bottomed stock pot, and set aside the rest of the oil and seeds. Turn heat to high, and brown meat all over. Take the pot off the heat, take out meat and reserve on a plate, strain the rest of your oil into your stockpot, and lower your burner to low. Place the pot back on the burner, add vinegar dash, and deglaze your pan.
Add your chopped vegetables, the remaining 1/2 tsp of cumin, and 1 tbsp of garlic salt and simmer over low heat for 15-20 minutes. When the vegetables are soft, place the meat and its juices back into the pot and cover it with water. Raise heat to high, cover, and bring to a rolling boil. Take off the cover and boil for 1 hour.
Take the meat out and slice into 1/2 inch slices, put back into the pot with any juices that have accumulated, and add the coca cola, boil for another 2 hours approximately or until the meat is fork tender.
When it is done, take the meat slices out, strain the liquid into another bowl, wipe your original pot, so there are no vegetable bits, and discard the veggies if you like (or not, sometimes I don't strain, but it is a matter of personal taste). Return your cooking liquid and the meat to the pot and cook for a little more if the sauce needs thickening.