These tangy-sweet buttery rhubarb lemon cookies are the perfect taste of spring.
In a large mixing bowl, cream the butter. Add the sugar and blend together until fluffy. Add the egg, vanilla, and lemon rind, and mix until thoroughly combined.
In a smaller bowl, combine the flour, baking soda, baking powder, and salt. Add the flour mixture gradually to the butter-sugar mixture, stirring after each addition to incorporate. Then stir in the diced rhubarb.
Scoop the dough in rounded teaspoonfuls onto a cookie sheet lined with parchment paper. The cookies will spread out a lot on the baking sheet, so make sure to leave plenty of room between the cookies. (Plan on no more than 8 to 10 cookies per pan.)
Bake the cookies in a preheated 325 degree oven for 20 minutes, or until golden brown and crispy. Let cookies cool on a pan for five minutes, then use a spatula to transfer them to a baking rack where they can continue to cool.