Three Yolk Steamed Eggs (Sam Wong Dan)

Have you ever heard that the skills of truly great chefs are tested by the simplest dishes?  I'm not a great chef, but I get it.  Egg dishes always require precision and timing.  Poached eggs, soft boiled eggs, hollandaise sauce, shirred eggs, and my foe...the steamed egg.
My steamed eggs have always come out dry, with the liquid separated from the eggs.  After much trial and error (and many dozens of eggs), I have finally managed to achieve that silky, smooth consistency. The secret is a slow simmer.  You just can't rush this dish.
I am somewhat of a purist, so I don't add much seasoning to this dish.  Besides, the saltiness from the salted duck egg will be flavor enough.

Three Yolk Steamed Eggs (Three Emperor Steamed Eggs)
4 large chicken eggs
1 salted duck egg, raw
1 century egg
water

Separate the whites and yolk from salted duck egg.  Carefully crack open the chicken eggs so that you can save one of the half shells for measuring out the water needed.  Add the whites from salted duck egg with chicken egg.  Add 12 half shells of water.  Whisk until blended.  If you want, you can strain the whisked egg mixture through a fine sieve to reduce air bubbles for a smoother surface.  I didn't do that since the slow simmer eliminated most of the air bubbles.  Pour mixture into heat proof bowl that is smaller than the pot that you are using.
Dice up the yolk from the salted duck egg.  Dice up the century egg.  This is when an egg slicer comes in really handy.
Stir salted duck egg yolk and century egg into whisked egg mixture.  Fill a large pot of water with 2 inches of water.  Place a steam rack in the center of the pot.  Heat the water to boiling and then reduce to a slow simmer.  Carefully place the bowl of egg mixture on top of the steam rack.  Cover.  Maintain the slow simmer for 10-12 minutes.  Serve immediately with steamed rice.