Preheat oven to 375 degrees.
In a large mixing bowl, whip the egg whites until white and foamy. Add the cream of tartar and salt and continue whipping until soft, droopy peaks form. Still whipping, add 1 cup of the sugar in a thin stream and whip until stiff and glossy. Sift the remaining 1/2 cup sugar and the flour together 3 times to aerate and lighten the mixture. Work quickly so the egg white does not deflate (or sift through a strainer onto a sheet of waxed paper). Fold into egg whites 1/3 at a time. Fold in the vanilla and tangerine zest. Gently spoon the mixture into an ungreased tube pan. Smooth the top and bake 30 to 35 minutes, until golden brown.
Glaze: Whisk together the tangerine juice and egg whites, then add the confectioners' sugar and stir until smooth.
Remove cake from oven and turn the pan upside down and hang it around the neck of a wine bottle to cool to room temperature. Slide a butter knife around the sides of the pan and put a serving plate on top. Turn over and knock the cake out onto the plate. (The browned crust of the cake will stick to the pan.) When the cake has cooled thoroughly, make the glaze and drizzle the glaze evenly over the cake. Let set in a cool place.
Courtesy Gale Gand, ?American Brasserie? by Gale Gand, Rick Tramonto, Julia Moskin, MacMillian Inc, 1997