Arrange oven racks in the top third and bottom third of the oven. Heat the oven to 175 degrees F. Line a large heavy baking sheet with parchment. Sift together the confectioners' sugar, superfine sugar, and salt.

With an electric mixer fitted with the wire whisk, combine the egg whites and cream of tartar. Begin mixing on medium-low speed until frothy. Increase the speed to medium high and beat until the whites form soft peaks. Continue beating while gradually sprinkling in the sifted sugars. When all the sugar is added, increase speed to high and whip until firm, glossy peaks form. Add the vanilla and the 1/3 cup pistachios and beat just until blended, about 10 seconds.

Spoon about half of the meringue into a large pastry bag fitted with a large (#8) star tip. Pipe shapes as you like (for kisses, about 1-1/2 inches wide and about 2 inches from tip to base) onto the prepared baking sheet, about 1/2 inch apart. If the tip gets clogged with a nut, use the back of a small knife or spoon to pry open the points of the star tip slightly and the nut will wiggle out. Sprinkle the toasted coconut over the meringues along with a dusting of pistachios, if you like.

Bake the meringues until dried and crisp but not browned, about 3 hours. Turn off the oven (leave the door shut) and let the meringues sit in the oven for about 1 hour. Remove them from the oven and gently lift the meringues off the parchment. Serve immediately or store in an airtight container for up to a month.