Preheat oven to 325º.
Pour boiling water over tea leaves in a bowl; steep 5 minutes. Strain through a fine sieve into a bowl; cool tea to room temperature.
Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour and 3/4 cup sugar, stirring with a whisk. Place egg whites in a large bowl; beat with a mixer at high speed until foamy. Add cream of tartar and salt; beat until soft peaks form. Add 3/4 cup sugar, 2 tablespoons at a time, beating until stiff peaks form. Beat in brewed tea.
Sift about 1/4 cup flour mixture over egg white mixture; fold in. Repeat procedure with remaining flour mixture, 1/4 cup at a time.
Spoon batter into an ungreased 10-inch tube pan, spreading evenly. Break air pockets by cutting through batter with a knife. Bake at 325º for 50 minutes or until cake springs back when lightly touched. Invert pan, and cool completely. Loosen cake from sides of pan using a narrow metal spatula. Invert cake onto a plate.