Put the rice in a 2-quart saucepan and barely cover with cold water. Bring to a brisk boil over high heat, and then immediately remove from the heat. Drain the rice in a colander, but do not rinse. Set aside.

In the same saucepan, over medium-high heat, bring the milk to a boil with the cinnamon and citrus peels. Once bubbles break the surface, return the rice to the pan and then add the sugar, stirring to break up any clumps of rice and dissolve the sugar.

Reduce the heat and simmer, partly covered, for about 40 minutes, or until most of the milk is absorbed and the rice is still chewy. Stir occasionally to prevent the rice from burning or clumping, and to prevent a thick skin from forming on the surface.

Have 4 flan or dessert cups ready.

Discard the cinnamon stick and citrus peels. Divide the pudding among the bowls with a ladle. Let cool and then refrigerate for at least 1 hour. If desired, dust the surface of each with ground cinnamon immediately before serving.