Place the milk, rice, cinnamon stick, orange or lemon peel and salt in a medium saucepan and bring to a boil over medium heat. Immediately reduce heat to very low and simmer, stirring often and scraping bottom, for about 45 minutes.

Add the raisins and sugar and simmer for another 15 minutes. Stir often to keep from sticking to the bottom of the pot.

Remove from heat and stir in the butter and vanilla. Adjust sugar to taste and serve hot or cold, sprinkling the top with some ground cinnamon.