Place all ingredients in a large stockpot. Bring to a boil over high heat. Reduce the heat to low and skim off any foam that appears on the surface. Let it simmer gently, uncovered, for about 1.5 to 2 hours. Strain the broth through a fine-mesh sieve or cheesecloth into a clean container, discarding solids. Let it cool before storing in the refrigerator or freezer. Use as a base for soups, stews, or enjoy on its own.