Step 1: Rinse pork bones thoroughly under cold running water to remove any bone fragments or impurities.
Step 2: Par-boil the bones: Place bones in a large stockpot, cover with cold water, and bring to a rolling boil. Boil for 15-20 minutes, skimming off any scum. Drain the bones and discard the cloudy water.
Step 3: Rinse each bone individually under cold water, scrubbing off any remaining scum or dark bits. Clean the stockpot thoroughly.
Step 4: Preheat oven to 400°F (200°C). Arrange blanched bones on a baking sheet and roast for 30-45 minutes, or until lightly browned. This step enhances the depth of flavor.
Step 5: Return roasted bones to the clean stockpot. Add the roughly chopped yellow onion, smashed garlic cloves, and sliced ginger.
Step 6: Add the dried kombu and dried shiitake mushrooms to the pot.
Step 7: Pour in enough cold water to cover all ingredients by at least 2-3 inches (approx. 5-6 liters total, depending on your pot size).
Step 8: Bring the pot to a boil over high heat, then immediately reduce the heat to the lowest possible setting to maintain a very gentle simmer. The surface of the broth should barely ripple.
Step 9: Simmer gently for a minimum of 8-12 hours, up to 18-24 hours for a richer, creamier broth. The longer the simmer, the more flavor and body will develop.
Step 10: Throughout the simmering process, periodically skim any foam or impurities from the surface. Replenish water as needed to keep the bones fully submerged.
Step 11: After desired simmering time, carefully remove all solid ingredients from the pot using a slotted spoon or tongs. Discard bones, kombu, shiitake, and aromatics.
Step 12: Strain the broth through a fine-mesh sieve lined with cheesecloth into a clean heatproof bowl or container. This removes any small particles for a smooth broth.
Step 13: Allow the broth to cool completely at room temperature before transferring to the refrigerator. Once chilled, any solidified fat on top can be skimmed off if desired.
Step 14: Your ultimate ramen broth is now ready to be used! Store in the refrigerator for 3-4 days or freeze for up to several months in airtight containers.