Place the sugar in an 8-inch ring mold.Place the mold directly over medium heat.Keep turning the mold until the sugar melts into a golden brown caramel and spoon it up the sides of the mold.
Combine the condensed milk,orange juice,orange zest, and eggs in a blender. Whip until smooth.Pour this mixture into the mold and place it in the center of the roasting pan with water. Bake the pudim for about one hour (it will depend on your oven).It will turn golden brown on top and start separating from the sides of the mold.Let it cool to room temperature and place in refrigerator, preferrably overnight (at least 6 hours).
Just before serving, run the tip of a knife around the inside of the mold. place a deep platter over the mold and invert (the pudim should slide out easily).If not, give the mold a firm but careful shake.Spoon the caramel sauce on top and serve.