Place the butter and water in a saucepan. Bring to a boil, remove from heat and whisk in the cocoa powder. Sift together the sugar, quinoa flour, baking powder, baking soda and salt. Add the cooled cocoa mixture, egg yolks, vanilla and sour cream and blend well. Beat the egg whites until stiff but not dry. Fold into batter.
Spoon into a muffin tin lined with paper cupcake liners. Bake for 20 minutes, or until a cake tester inserted in center comes out clean.