6 unpeeled carrots, cut into thirds
2 unpeeled yellow onions, cut into chunks
1 leek, cut into thirds
1 bunch celery, including the heart, cut into thirds
4 unpeeled red potatoes, quartered
2 unpeeled Japanese or regular sweet potatoes, quartered
1 unpeeled garnet yam, quartered
5 unpeeled cloves garlic, 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, filtered water
1 teaspoon sea salt
Rinse all the vegetables well, including the kombu. In a 12-quart or larger stockpot, combine the carrots, onions, leek, celery, potatoes, sweet potatoes, yesm, garlic, parsley, kombu, peppercorns, allspice berries, and bay leaves. Fill the pot with the water to inches below the rim, cover, and bring to 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. Simmer until the full richness of the vegetables can be tasted. Strain the broth through a large, coarse-mesh sieve (remember to use a heat-resistant container underneath), then add salt to taste. Let cool to room temperature before refrigerating or freezing.