Step 1

Place the bones in a large stockpot and cover with cold water. Bring to a boil over high heat and simmer for 15-20 minutes before draining and rinsing the bones with water. DO NOT SKIP THIS STEP.

Step 2

Preheat the oven to 450 degrees F. Spread rinsed bones, onion, garlic, and ginger into an even layer in a roasting pan. (Use two pans if you cannot make an even layer in one) Roast for 60 minutes stirring once halfway through.

Step 3

As the bones are roasting, add all star anise, cinnamon, cloves, cardamom pods, coriander seeds, and fennel seeds to a large, dry skillet over low heat. Toast your spices, stirring often to prevent burning, until fragrant, approximately 5 minutes. Make a spice sachet by transfer to your cheesecloth and gathering at the top and tying with kitchen twine.

Step 4

Transfer the bones into a slow cooker. Scrape bits and juices remaining in the roasting pan into the pot with the bones. (*see note)

Step 5

Cover bones with water and add spice sachet, 1/2 cup fish sauce and 3 tablespoons sugar. Cook on low for 12-24 hours, occasionally skimming the fat and foam from the top of the pot. Add more water if the bones do not stay submerged.

Step 6

Strain the broth through a fine mesh strainer. At this point you can cool the broth completely, place in airtight containers and freeze for future use. Or, prepare the soup. (**see note)

Step 7

Wrap beef in plastic wrap, and place in the freezer for about 1 hour.

Step 8

Meanwhile, fill a large bowl with cold water; add rice noodles. Let soak until soft, about 30 minutes. Drain; set aside.

Step 9

Remove beef from freezer. Using a mandoline or a very sharp knife, slice beef into very thin (1/8 inch) strips.

Step 10

Divide noodles among six serving bowls, and arrange strips of meat over them. Bring stock to a boil if chilled. Pour boiling stock over meat and noodles, pushing beef into hot liquid so that it cooks. Arrange bean sprouts and other garnishes over beef and noodles; serve immediately.