Preheat oven to 350 degrees F (175 degrees C) Grease cookie sheets. Set aside.
Spread sesame seeds in 9x9 inch baking pan. Toast in the oven for 10 to 15 minutes. Remove from oven and cool. Increase oven temperature to 375 degrees F (190 degrees C).
Melt butter and cool a bit. Stir in sugar, lemon rind, egg, sesame seeds, flour, and baking powder.
Drop by 1/2 teaspoonfuls onto cookie sheets, leaving about 2 inches between each cookie. Bake for 10 minutes or until golden brown. Cool for 1 to 2 minutes before removing from cookie sheets. Cool cookies on wire racks.