1. Boil: Place the lamb shank bone into a large stockpot and cover entirely with the 6 quarts of water. Bring to a boil over high heat. Once boiling, reduce the stove heat down to medium.

2. Add Aromatics: Stir in the chopped celery, carrots, onions, diced tomatoes, salt, peppercorns, and bay leaves.

3. Simmer: Partially cover the pot with a lid. Let it simmer gently for 1 to 2 hours, allowing the liquid to reduce and develop a rich flavor.

4. Taste Test: Taste the stock near the end of cooking. If the flavor feels a little weak, simply turn up the heat slightly and let the liquid boil down and reduce further.

5. Strain: Set a large colander or fine-mesh strainer over a massive mixing bowl. Carefully pour the contents of the pot through the strainer to catch the liquid.

6. Discard: Discard the spent shank bone, vegetables, and bay leaves.

7. Skim: Use a ladle to skim off any excess fat that floats to the top of the strained liquid.

8. Store: Use the stock immediately, or let it cool before storing. Refrigerator: Keeps well for 3 to 4 days. Freezer: Freeze in airtight containers for up to 2 months.

9. Be sure to label and date your container.