Fill a large 8 to 9-quart stock pot halfway with water and bring to boil. While waiting for the water boil, fill a large bowl with warm water and soak the 2 pounds beef bones and 2 pounds beef shank (or oxtail). When the water boils, drain the water and add the bones to the pot of boiling water. Boil the bones for 10 minutes. During the last few minutes, use a ladle to scoop out the fat and blood particles and dispose of them in an old jar or milk container.

After 10 minutes of parboiling the beef bones, place a large colander in your sink and strain the bones, rinse the bones to remove any blood, and clean the pot. Add the cleaned bones back into the pot and refill the pot with cold water. Don't overfill the pot, allow 1-2 inches for the soup to boil without bubbling over. You can add more water later.

While waiting for the bones to boil, prepare 1 large onion and 1 3-inch piece ginger for roasting or charring. Peel off the outer layers of the onions, cut in half, and trim the root end of the onion slightly so that it stays intact. Split the ginger in half lengthwise. Place the pieces of onion and ginger in a frying pan and dry roast them until they are slightly charred. Option: If you have a gas stove, you can hold them with a pair of metal tongs and roast them over an open flame. Once the ginger and onion pieces are slightly charred, add them to the pot of water and bones.

Preheat a clean dry frying pan on low-medium heat for a few minutes. While waiting use a nut-cracker to crack open 1 piece cardamom (black). Toast the spices, 1 3-inch piece cinnamon stick, 3 pieces star anise, 1 teaspoon coriander seeds, 1 teaspoon fennel seeds, 1 piece cardamom (black), and 3 pieces cloves in a clean dry frying pan until the spices fragrant, about 30 seconds to 1 minute in a warm pan. Transfer the spices in a mesh bag, wrap with a piece of cheese cloth and kitchen string, or place in a large spice ball. Set aside to add to the soup during the last hour of simmering.

When the pot of water and bones come to a boil, lower the temperature between low and low-medium, to simmer the broth in the pot for 3 hours un-covered. Remove any foam, blood, or excessive fat with a spoon or fat skimmer.

While the broth is simmering, prepare the garnishes. Chop ½ large onion and then soak in cold water for 10 minutes and drain, set aside. Chop 1 bunch scallions and 1 cup cilantro (if using), set aside. Arrange 4 cups mung bean sprouts, 6 springs Thai basil, lime wedges, and jalapeño slices on a serving plate, set aside.

If you need to slice the raw beef (rib eye, filet mignon, or eye of round), place it in the freezer for 30-60 minutes before slicing. Pat the sliced beef with paper towels to blot some of the excess blood.

If using dry rice stick noodles, cook the 1 14-ounce package bahn pho (rice noodles) according to the package instructions, until soft, and then drain in a colander and rinse. If using fresh rice noodles, add to a large pot of boiling water, stir, and immediately strain in a colander and rinse with cold water.

After the 2 hours of simmering, add 1.5 teaspoon salt, 1 ounce rock sugar (ping pong ball size) , and the spice ball and continue to simmer the broth. After 3 hours, remove and discard the spices, transfer the cooked hind shank meat, oxtail pieces, and marrow pieces to a clean serving bowl and cover with 1-2 ladles of broth to keep the meat from drying out, remove the beef bones (set aside). Taste to see if the broth needs any more sugar or salt and add 1-2 teaspoons as desired. Increase the heat and bring the pho broth to a rolling boil.