Add beef bones to a large pot that will hold at least 10 quarts. Then, cover bones with cold water. Place pot onto high heat and bring to a boil. Boil for 3 to 5 minutes. During this time, impurities and foam (or scum) will be released and rise to the top. Drain bones, discarding the water. Then, rinse bones with warm water and scrub stockpot to remove any residue that has stuck to the sides. Add the bones back to the stockpot and cover with 6 quarts of cold water.

Meanwhile, move an oven rack to a high position then turn broiler to high. Line a baking sheet with aluminum foil. Place quartered onions and halved ginger onto baking sheet then broil for 10 to 15 minutes, turning onions and ginger occasionally so that they become charred or browned on all sides.

Add cinnamon sticks, coriander seeds, fennel seeds, star anise, cloves and the black cardamom pod to a dry frying pan. Place onto low heat and cook, stirring occasionally until fragrant. About 5 minutes. Place toasted spices into a cotton muslin bag/herb sachet or cheesecloth then tie with butchers twine to seal.

Bring stockpot with parboiled bones and water to a boil then lower to a gentle simmer. Add charred onion and ginger as well as the bag or sachet of toasted spices. Add 1 1/2 tablespoons of salt, a 1/4 cup of fish sauce and the rock sugar. Continue to simmer broth, uncovered, for 3 hours. If at any time foam or scum rises to the surface, use a spoon to remove it.

Use tongs or a wide mesh spoon to remove bones, onion and ginger from broth then strain broth through a fine mesh strainer. The broth will have a layer of fat at the the top. There are two ways to remove this. First, if you plan to enjoy the broth now, skim the fat from the top of the broth using a spoon. If you do not mind waiting, you can also pour broth into containers then refrigerate overnight. As the broth cools, the fat will solidify, making it very easy to remove.

ASSEMBLY
Bring the broth to a gentle simmer over medium heat.

If you are using dried noodles, add noodles to a bowl then cover with hot water and soak for 15 to 20 minutes until soft and opaque. If you are using fresh, add to a colander then rinse with cold water.

To cook the noodles, bring a medium saucepan filled with water to a boil. Place noodles into boiling water and cook for about 10 seconds or until they collapse. Drain noodles then divide between bowls. (We like to fill each bowl by 1/3 with noodles).