Preheat the oven to 350 degrees F.
Line two baking sheets with parchment paper.
Sift 2 1/4 cups all purpose flour into a medium bowl.
Add 1/2 tsp baking powder and 1/4 baking soda into the sifted flour. Whisk to combine.
These cookies can be mixed by hand or with a mixer. If using a stand mixer, add the paddle attachment.
Add the tea, lavender, and sugar to the bowl of the mixer.
Work the tea and lavender into the sugar by rubbing them between your fingers. Make sure the tea leaves are a reasonable size (mine started out rather large) for eating.
Beat together the butter and sugar until thoroughly combined.
Add the egg and mix to combine.
Pour in the vanilla and mix.
Slowly add the dry ingredients and mix on low speed until combined. Be sure to scrape down the sides of the bowl.
Using a cookie scoop or a tablespoon, scoop out the dough and place on the prepared cookie sheets about 1 1/2 inches apart.
Bake for 12-14 minutes, rotating the pans midway through, until the edges are golden.
Allow the cookies to cool on the tray for 5 minutes, then transfer to a wire rack.
Prepare the glaze while cookies cool, sifting the confectioners sugar and combining it with fresh lemon juice in a small bowl.
Dip the tops of the cooled cookies in the glaze and allow to dry. Sprinkle with a tiny bit of lavender if desired.