Preheat oven to 350°F (175°C).

Roast the unpeeled onion and ginger on a baking sheet for 1 hour, until softened and oozing.

Cool onion and ginger, then peel the onion and slice the ginger.

Blanch the oxtails, neck bones, and shanks in boiling water for 3 minutes.

Rinse the blanched bones under cold water.

Return the rinsed bones to a large pot and add the marrowbones.

Add the roasted onion halves, ginger slices, palm sugar, salt, and 8 quarts of fresh water to the pot.

Bring to a boil over high heat and skim off any scum.

Reduce heat to a gentle simmer and simmer for 4 hours, skimming as needed.

Add the white pepper, cinnamon, star anise, clove, and cardamom to the pot.

Continue simmering for 1 hour, skimming occasionally.

Remove from heat and discard the large solids.

Strain the stock through a fine-mesh sieve into a large container.

Let the stock sit for a few minutes, or refrigerate overnight.

Skim most of the fat from the surface (leave some for flavor).

Use immediately, or cool completely and transfer to airtight containers.

Refrigerate for up to 3 days or freeze for up to 3 months.