There are many different iron designs, and different batter recipes to try. With the irons I received for Christmas I tried the following recipe:
Basic Batter - makes 36 rosettes
-225ml milk
-1 vanilla bean, split lengthwise
-3 tablespoons granulated sugar
-1/2 teaspoon coarse salt
-1/2 teaspoon ground cardamom
-175g all purpose flour
-2 large eggs, beaten
-Oil for frying
-Icing sugar for dusting
1. Scrape the seeds from the vanilla and whisk with the milk. In a separate, larger bowl, mix together the sugar, salt, cardamom and flour. Add the milk and eggs and whisk until smooth. Chill the batter for 30 minutes.
2. Heat the oil in a deep frying pan or large saucepan until the temperature reaches 375°.
3. Carefully dip the irons (with handle attached) into the oil and leave to heat for 2-3 minutes. Blot on a paper towel. At this point it is handy to have some paper towels laid out on the work surface, as it can get messy!
4. Dip the hot iron into the batter up to the top edge of the iron- do not totally submerge. Then dip into the hot oil for around 15 seconds or until golden brown. Remove from the oil and gently remove the rosette, using a fork if required. The rosette may detach itself from the iron whilst it is still in the oil, in this case carefully remove from the oil with tongs. Drain the rosettes on paper towels then serve dusted with icing sugar.
A video on how to make them can be found here: http://www.youtube.com/watch?v=dxAKDEV3UuM