It's up to you whether to peel the ginger (2 lb) or to leave the peel on. If you decide to leave the nutritious peel on, make sure to wash the ginger extra thoroughly.

If the ginger is large, halve it or cut into more manageable chunks. Then use the side of your knife to lightly smash each piece of ginger. This will help extract the flavor into the soup.

Then, cut the ginger into slices about 1/4-in thick.

We'll be parboiling the pork knuckles to remove impurities. Don't skip this step, or your soup will end up tasting gamey, feeling grimy, and looking cloudy!

Add about 5 cups of cold water to a pot, or enough to cover the pork knuckles. Turn the heat to high, add the pork knuckles (2 lb), and cover with a lid.

Once the water comes to a boil, uncover the pot and turn the heat down to medium. Use chopsticks to gently move the pieces of meat around to ensure even cooking.

You'll start to see foam and scum boiling out of the pork knuckles and coming to the surface. This parboiling step is meant to extract all of this gunk out from the bones; we won't actually be cooking the meat through. No need to skim while it's still boiling; we'll rinse it all off soon.

Continue to boil at medium heat for 2-3 minutes. Then, turn off the heat and carefully transfer the pork to a large bowl of clean, cold water.

Place the bowl in the sink, and gently scrub the pork knuckles with your hands to get more of the scum off. It's easiest to get them clean if you rinse them under cool running water as well. Then, drain the water and set them aside.

In a clean, dry wok (we recommend stainless steel or some other nonreactive material) on medium heat (no oil!), cook the sliced ginger and toast the pieces for about 5 minutes, stirring and flipping the pieces for even cooking, until the ginger has darkened in color and the edges are slightly charred, and it smells very aromatic. Turn off the heat.

This step helps remove the moisture from the ginger so the pieces can better absorb the vinegar later. There's no need to preheat the wok or use high heat; doing so may burn the ginger.

Add sweet black vinegar (2.5 lb) to the wok. Then turn the heat to medium, and stir to combine. This vinegar is added for sweetness.

Add Zhenjiang black vinegar (3 fl oz) and stir. This vinegar is for sourness.

Turn the heat to high, add the rock sugar (1 oz) and salt (1 tsp), and stir to incorporate. The sugar helps to mellow out the tartness of the vinegar, and the salt brightens that sour flavor.

Then turn the heat down to medium-low and cook with the vinegar for 2 minutes.

Cover with the lid, and continue to cook for 5-7 minutes on low heat.

Give the soup a quick taste and adjust the flavor to your liking; add sugar if you'd like it to be sweeter, or more vinegar if you'd like it more tart. Then cook for about 4-5 minutes, uncovered. Give it an occasional stir to move the ginger around.

You can start making the boiled eggs while you're waiting for the soup to cook. Or, you can boil them farther in advance. It's up to you and your schedule.

To boil the eggs, start with the eggs in a pot, submerged in cold water. Boil the eggs for 5 minutes, then turn the heat off. Continue to let the eggs cook with the heat off for 5 minutes, then remove them from the pot and immediately transfer them to a large bowl of cold water.

Let them soak in the cold water so that the egg has a chance to shrink back from the shell, and they'll be super easy to peel. You'll want to peel them right before you're ready to add them to the soup.

This results in firm egg yolks, which is our preferred level of doneness for this dish, but you can adjust the cooking time if you prefer your boiled eggs a little softer or a little firmer.

If you don't have a clay pot, you can continue cooking it in a vessel made of non-reactive material. Preference for the clay pot is both traditional and utilitarian; clay is non-reactive while still great at retaining heat.

First, transfer the ginger over. Make a layer of sliced ginger on the bottom of the clay, then scoop the rest in. The ginger at the bottom will be the first to receive heat, allowing it to release its flavor best. Also, it forms a cushy barrier to keep the pork knuckles from sticking to the pot and burning.

Then, don your protective gear, carefully pick up your wok, and pour all of the vinegar mixture into the clay pot.

With clay pots, please remember to keep the heat to a medium-low, preferably over a flame rather than direct heat.

Turn the heat to medium-low, cover the pot, and bring it to a boil. Once it starts to boil, add the pork knuckles. Layer the bones towards the bottom; the idea is that they'll soak better lower down, and the vinegar will be better able to extract that nutritious calcium.

If necessary, add more sweet vinegar. The liquid should cover all of the pork knuckles.

Continue cooking for at least an hour. When you're ready to eat it, you can add the eggs. The eggs can soak for a while. We like to let them cook in the stew for an hour, though if you'd rather they be less well-done, you can add them for a shorter amount of time. The longer they soak, the more flavor they'll absorb.

Traditionally, this stew keeps for days, even weeks! In the chaos of bringing a newborn home, families simply reheat the stew when they need a ready meal or a snack.