To make the cake:
Have ready a 10-inch tube pan with removable bottom and a bottle over which the pan can be inverted when it comes out of the oven. Remove all but the bottom rack and preheat oven to 350 degrees.
Rinse and dry the cranberries. Sift flour once and then sift again three more times with 1/2 cup of the sugar. Set aside while preparing the rest of the ingredients. Sift the remaining 1 cup sugar separately and keep aside in a small bowl. Grate the orange zest.
Place egg whites in a large bowl, preferably that of a KitchenAid or similar mixer. Using the whisk attachment, whip the egg whites until frothy, about 30 seconds. Add the cream of tartar and salt and continue whipping until soft peaks form. With the mixer running, gradually add the 1 cup sugar and beat until the mixture is stiff and shiny, but not dry.
Sift about one third of the flour-sugar mixture over the egg white mixture and gently fold this in with a spatula. Repeat until all the flour-sugar mixture is incorporated. Then fold in the vanilla, orange zest, and cranberries.
Spoon the batter into the ungreased tube pan. Gently run a knife through the batter to remove any air pockets. Bake for 35 to 40 minutes, until golden brown on top. Immediately invert the pan onto the bottle and let the cake cool completely, about 1 1/2 – 2 hours.
Run a thin sharp knife around the insides of the pan and the middle tube section, remove the base with the cake, and then use the knife to loosen the cake from the bottom. Carefully remove the cake completely from the pan and place on a platter, with the flat, narrower side up. The cake can be made up to a day ahead, but do not glaze it until close to serving (a few hours in advance is okay).
Place the confectioners' sugar and juices in a small bowl and whisk until blended. Pour the glaze over the top of the cake and gently spread with a spatula just to the edges, so that the glaze trickles down the inner and outer sides. Let set for at least 30 minutes in a cool place before serving. Some of the glaze will settle at the bottom of the cake. This is fine, but if you want to prevent this, carefully slide four narrow pieces of wax paper under the cake all around it before glazing. This will catch the excess glaze as it drips down. When ready to serve, gently slide out the strips of wax paper.
This cake should be cut with a serrated knife, using a gentle sawing motion.
Yield: About 16 servings