Start by washing all your vegetables thoroughly to remove any dirt or debris. Cut the celery head into 3-inch pieces from the roots to the leaves, then add them to your large stock pot. Quarter the carrots and onions—leave all roots and skin on the carrots, but remove just the onion roots. Add these vegetables to the pot along with your prepared celery.

Slice the head of garlic in half width-wise so all the cloves are exposed, then add both halves to the stock pot without peeling. Add all the fresh herbs—thyme, rosemary, and sage—along with the bay leaves and whole peppercorns to the pot. If you're adding salt, include it now, though leaving it out gives you more flexibility when using the stock later.

Pour the entire gallon of water over the vegetables and herbs in the pot. Bring the mixture to a boil over high heat, then reduce to low or medium-low and let it simmer for 1 hour. The slow simmer extracts all the wonderful flavors from the vegetables without making the stock cloudy.

After an hour of simmering, remove the large vegetable pieces with tongs or a slotted spoon before straining. Set up a mesh strainer over a large bowl or another pot, then carefully pour the remaining stock through to catch any small bits. This double-straining process ensures a clear, beautiful stock.

Carefully fill your mason jars with the hot stock and seal them with lids immediately while the liquid is still hot. Let the jars rest on the counter for about 2 hours until they reach room temperature. Once cooled, retighten the lids and store them in the refrigerator.