Sift flour, soda, baking powder and salt.
Cream brown sugar and butter in mixer bowl until fluffy; beat in egg and vanilla.
Stir in flour mixture alternately with yogurt just until blended.
Spoon into greased 9-inch tube pan.
Bake at 350 degrees for 50 minutes or until cake tests done.
Cool cake in pan on wire rack for 10 minutes.
Loosen edges and center with knife; turn onto rack.
Sprinkle lightly with confectioner's sugar just before serving.