1 bunch celery, including the heart, cut into thirds
4 unpeeled red potatoes, quartered
2 unpeeled Japanese or regular sweet potatoes, quartered
5 unpeeled garlic cloves, halved
1/2 bunch fresh flat-leaf parsley
1 8-inch strip of kombu
12 black peppercorns
4 whole allspice or juniper berries
2 bay leaves
8 quarts cold water
1 teaspoon sea salt
Directions
Rinse all of the vegetables well, including the kombu. In a 12-quart or larger stockpot, combine the carrots, onions, leek, celery, potatoes, sweet potatoes, yam, garlic, parsley, kombu, peppercorns, allspice berries, and bay leaves. Fill the pot with the water to 2 inches below the rim, cover, and bring to a boil.
Remove the lid, decrease the heat to low, and simmer, uncovered, for at least 2 hours (. As the broth simmers, some of the water will evaporate; add more if the vegetables begin to peek out.
Strain the broth through a sieve, save broth and compost vegetables.
Let cool to room temperature before refrigerating or freezing.