How is this so? Wouldn't you be making an egg drop soup?
Here's what I found out.
* Using egg whites to clarify a stock/broth is a common technique used in making consommé.
* The egg whites will coagulate into a fine mesh that will "filter" the stock as it simmers.
* Egg whites seem to be the key, but you can add julienned veggies for flavor the broth and to provide the support for the egg white raft (the stuff floating on top of the liquid.)
* Common additions are crushed egg shell, ground meat, carrots, green onion and other typical flavorings that go into a stock.
* Thumbing through Julia Childs' book, The Way to Cook, she uses 4 egg whites for 5 cups of stock.
Here's my pho stock out of the fridge which I defatted by pouring through a fine mesh strainer. A good sign for the stock is the gelling from the refrigeration. This means a lot of flavor was squeezed out of the soup bones and more. :-)
I have five (5) cups remaining after serving pho on Monday.

Here’s what I did to clarify the Pho broth...
Green Onion, coarsely cut
1/4 C Daikon, shredded
1/4 C Carrots, shredded
1/4 C lean Beef, minced (trim off the fat)

Two egg whites were whipped into a soft foam. I know Julia suggested using 4 egg whites, but that just seems like too much. In other words, I’m being cheap. Lol!

Mixed all the ingredients together into the egg whites.

The egg white concoction was thoroughly mixed into the cold broth.

The broth was slowly brought to a simmer and allowed to simmer for about 35 minutes.

Wow! It worked!
I'm about to decant the broth into a colander lined with a coffee filter.

Before Clarifying (From Monday)

I would say it was a success. The muddiness is gone and now the broth is transparent. The broth looks like apple juice or apple cider vinegar. The extra ingredients also added more flavor to the so-so broth.
After Clarifying (Today)

More Info…
I found this discussion about clarifying broths using egg whites.
Also, it looks like someone watched the Iron Chef episode and was curious about clarifying broth too. :-)
http ://forums.egullet.org/index.php?showtopic=112366
Another method - you can clarify using gelatin instead of egg whites.
My post from Oct 3: http://eat4fun.blogspot.com/2008/10/oct-03-experiment-clarifying-stock-with.html