Preheat the oven to 325 degrees F (170 degrees C) and have ready a 10 inch (25 cm) two piece tube pan (ungreased).

In the bowl of your electric mixer, fitted with the paddle attachment, place the flour, sugar (minus 3 tablespoons (42 grams)), baking powder, and salt.  Beat until combined.  Make a well in the center of the flour mixture and add the egg yolks, oil, orange juice, orange zest, and vanilla extract.  Beat about one minute or until smooth. 

In a separate bowl, with the whisk attachment, beat the egg whites until foamy.  Add the cream of tartar and continue to beat until soft peaks form.  Gradually beat in the remaining 3 tablespoons (42 grams) of sugar and beat until stiff peaks form.  With a large rubber spatula or wire whisk, gently fold the egg whites into the batter just until blended (being careful not to deflate the batter). 

Pour the batter into the ungreased tube pan and bake for about 55 to 60 minutes, or until a wooden skewer inserted into the center of the cake comes out clean.  (When lightly pressed the cake will spring back).  Immediately upon removing the cake from the oven invert the pan and place on a bottle or flat surface so it is suspended over the counter.  Let the cake cool completely before removing from pan (about 1 1/2 - 2 hours).

To remove the cake from the pan, run a long metal spatula around the inside of the tube pan and center core.  Invert onto a greased wire rack.

Can store in an airtight container for a few days at room temperature or for about a week in the refrigerator.  This cake can also be frozen for a couple of months.