In a bowl, beat together butter, sugar, tea leaves and zest until light; stir in flour, cornstarch and salt. Knead to make a smooth dough.

Between sheets of wax paper, roll out dough to 1/4 inch thickness. Using a 2 to 3-inch leaf cookie cutter, cut out shapes, re-rolling scraps. Place on parchment lined baking sheets. Drag knife down the center to create vein. Chill until firm, about 30 minutes.

Bake in preheat 325ºF oven until firm and golden, about 16 minutes. Cool on pans for 5 minutes, transfer to cooling racks and let cool completely.