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Preheat oven to 375 degrees.
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Sift together 1 cup flour and 1/2 cup sugar.
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In a large bowl, beat egg whites until foamy.
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Add cream of tartar and salt and continue beating until soft peaks form.
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Add 1 cup of the sugar, 2 tablespoons at a time and continue beating until stiff peaks form.
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Sift flour mixture over the egg whites, 1/4 cup at a time, folding in carefully.
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Fold in vanilla and blueberries.
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Combine 2 tablespoons flour and lemon zest then fold this into the egg white mixture.
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Spoon batter evenly into an ungreased 10 inch tube pan.
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Bake for 40 minutes or until cake springs back when lightly pressed.
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Invert pan over a wire rack and allow to cool completely.
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Loosen cake by running a spatula around the edges of the pan, and remove from pan.
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To make the glaze, whisk the lemon juice and sugar together until it forms a smooth glaze then drizzle it over the cake.