Beat butter and sugar in large mixer bowl until light and fluffy. Beat in tea, egg yolk and vanilla extract. Gradually stir in flour. Drop by heaping teaspoon 2 inches apart onto ungreased baking sheets.
Bake 12 to 15 minutes or until lightly golden. Cool & brush with glaze. Cool completely prior to serving.
To make the glaze, combine all ingredients, and let thicken before brushing over cookies.