In saucepan, heat achiotina on medium low, stir in scallions and cook until soft – about three minutes. Stir in potatoes and cook for three minutes. Add the adobo, water and seasonings and bring to a boil on medium high. Reduce heat and simmer until potatoes are completely done – about 30 minutes.
With a wooden spoon, mash sever potato cubes against the side of the pan to thicken soup. Add milk and corn and return to boil. Simmer for 5 minutes. Stir in cheese and heavy cream. Heat until cheese melts and soup thickens.
Serve hot. Garnish with cubed ripe avocado, chopped boiled eggs and additional scallions, if desired.