Instructions

1. Parboil the bones and shanks: Place the bones and shanks in a large stockpot, cover with water, and bring to a boil over medium-high heat. Boil until a gray foam gathers on top, 5 to 10 minutes. Transfer the bones and shanks into a colander and discard the water. Rinse the bones and shanks under cool running water. Rinse out the stockpot and return the bones and shanks to the pot; set aside.
2. Char the onions and ginger: Arrange an oven rack directly under the broiler and heat to high. Line a baking sheet with aluminum foil. Peel and quarter the onions, halve the ginger hand and place on the baking sheet. Drizzle with the oil, toss to combine, and arrange in a single layer. Broil, stirring or rotating the pan every 3 to 4 minutes, until the onion and ginger are blackened, 15 to 20 minutes total. Set aside to cool.
3. Toast the spices: Place the star anise, cloves, coriander, fennel, and cinnamon in a large cast iron skillet over medium heat and toast, stirring frequently to avoid burning, until fragrant, about 2 minutes. Remove the spices to a small bowl and let cool. Secure the spices in a small spice bag or bundle made of cheesecloth.
4. Simmer the broth: Add the brisket, onion, ginger, and spice bundle to the stockpot. Add 1 gallon of water and bring to a boil over medium-high heat. Reduce the heat to a simmer and cook for 5 to 6 hours. While the broth is simmering, occasionally use a clean spoon to skim any gray foam from the surface. The broth is ready when it reduces by half and the brisket is fork-tender. The broth can be made up to a week in advance, or, if serving immediately, feel free to prepare the noodles, flank steak, and accompaniments while the broth cooks.
5. Strain the broth: Remove the brisket from the broth and reserve for serving with the finished soup. Add the fish sauce and brown sugar to the broth and stir to combine. Taste the broth. Does it need a little more salt or sugar? Make those adjustments now. Strain the broth through a fine-mesh strainer or a colander lined with cheesecloth set over a large bowl; discard the solids. The broth should be cooled and then chilled immediately for storing, or can be returned to a pot on the stove to return to a boil for serving.
6. Blanch the noodles: Place the rice noodles in a large bowl, cover with warm water, and soak. Meanwhile, bring a large pot of water to a boil. Drain the noodles and add them to the boiling water. Cook until tender, 1 to 2 minutes. Drain and set aside until ready to serve.
7. Freeze the flank steak: Place the flank steak on a plate and freeze 15 minutes.
8. Slice the flank steak: Thinly slice the flank steak across the grain; you may find a serrated knife works best for this. Cover and store in the refrigerator until ready to use.
9. Prepare the accompaniments: Slice the reserved brisket. Make a small tray of the herbs, chiles, limes, sprouts, and sauces.
10. Prepare pho bowls: Divide the noodles, brisket, raw flank steak, and scallions among wide, deep bowls.
11. Boil the broth: Bring the broth back to a boil over medium-high heat. Top each bowl with the boiling broth.
12. Serving and eating: Put the condiments in a small bowl on the side for dipping meat, as to not ruin the flavor of the broth.