How to Make It
Preheat oven to 375°.
Sift together 1/2 cup sugar and 1 cup flour.
In a large bowl, beat egg whites with a mixer at high speed until foamy. Add cream of tartar and salt; beat until soft peaks form. Add 1 cup sugar, 2 tablespoons at a time, beating until stiff peaks form.
Sift flour mixture over egg white mixture, 1/4 cup at a time; fold in. Fold in vanilla and blueberries.
Combine 2 tablespoons flour and lemon rind; toss to coat. Sprinkle over egg white mixture; fold in.
Spoon the batter into an ungreased 10-inch tube pan, spreading evenly. Break air pockets by cutting through batter with a knife. Bake at 375° for 40 minutes or until cake springs back when lightly touched. Invert pan; cool completely. Loosen the cake from sides of pan using a narrow metal spatula. Invert cake onto plate.
To prepare the glaze, combine powdered sugar and lemon juice in a small bowl; stir well with a whisk. Drizzle over cooled cake.