Preheat oven to 350.
Put flour, sugar and baking soda into a mixing bowl. Mix them together fairly well.
Grate all your lemon rind into a measuring cup.
Take your abused lemon, cut it in half and squeeze the juice from both halves into your measuring cup.
Next add water to your rind and lemon juice until you have filled one cup.
Pour your lemon juice mixture into your bowl of dry ingredients.
Add oil, vanilla and vinegar.
Mix well.
Pour into an ungreased 8 inch cake pan.
Bake 25 minutes, or until cake bounces back a bit when you touch its center.
Double the recipe for a 9x13 pan and add 10-15 minutes (approx) to the bake time.