Preparation Put all ingredients in a nonreactive stockpot. Bring to a boil and simmer slowly for 2 to 3 hours. Strain through a fine mesh sieve. The stock should taste concentrated and sweet. Cool and refrigerate. Chef's Tip:Charring Onions: There are several recipes, especially for stocks, that call for charred onions, which add complexity and subtle smokiness. If you have gas burners, then you can cut peeled yellow onions in half and burn the cut side over an open flame for a few minutes, until mostly blackened. If you have electric burners, you can either put the cut side of the onions directly on burners set to high, or put a piece of aluminum foil on the burner first, and then char the onion on top of the aluminum foil. Excerpted from Aroma (Artisan Books) Copyright 2004 by Mandy Aftel and Daniel Patterson