1. Preheat oven to 350°F.
2. In a bowl beat the yolks of the eggs and the sugar together until light and well mixed. Add the water, lemon juice, and grated lemon rind. Then add the flour and baking powder and mix all together well.
3. In a separate bowl, beat the whites of the eggs until stiff, then add them to the batter mixture and fold in gently.
4. Grease a mini muffin pan and add about a Tablespoon of batter to each.
5. Bake for 10 minutes. Remove from oven and cool.
6. Remove from muffin pan and roll lemon cakes in powdered sugar. Serve with warm lemon sauce.

For lemon sauce:

1. In a small sauce pan add the grated lemon rind, lemon juice, sugar, and corn starch. Stir until well blended.
2. Bring to a boil over medium heat stirring constantly.
3. Reduce heat to a simmer and cook for an additional 2 minutes, sauce will thicken.
4. Remove from heat and serve warm.
5. Refrigerate extra sauce for up to 1 week.