I did the research to make a consomme, and saw that tomatoes are a universal ingredient, which provide the necessary acidity for denaturing the egg whites and getting them to perform their filtration function. In Michael Ruhlman's account of making consomme at CIA, he describes how his professor used fresh winter tomatoes, which didn't have the necessary acidity, and resulted in a flawed consomme. He switched to canned, and it came out fine.
Then, in cross-referencing Shirley Corriher's "Cookwise" (I'm a bookish sort of cook) I was surprised to see that she does not include tomatoes, or any acidic ingredients, but only the stock, ground meat, leeks, and egg whites. There is no explanation for this omission. Could the infallible Shirley have gotten this one wrong? (It's true that in the preparation of the veal stock itself tomato paste and a small amount of wine is used, but this wouldn't seem to be enough).