Preheat your oven to 350°F (175°C).
In a bowl, sift together the gluten-free flour and half of the sugar. Set aside.
In a large mixing bowl, beat the egg whites until foamy. Add the cream of tartar and salt, and continue to beat until soft peaks form.
Gradually add the remaining sugar, a tablespoon at a time, beating until stiff peaks form. Beat in the vanilla extract.
Gently fold in the flour mixture, a little at a time, until fully incorporated.
Spoon the batter into an ungreased tube pan. Smooth the top with a spatula.
Bake for 40 minutes, or until the cake is golden brown and springs back when lightly touched.
Invert the pan and let the cake cool completely before removing from the pan.