Step 1

Set baking rack 8 inches below heating element. Turn oven to low broil. Place the onion and ginger halves, cut side up, on a baking sheet. Brush the halves with a little bit of oil. Broil until the onion and ginger slightly charred, about 10 minutes, turning half-way. Remove from heat and cool.

Step 2

Parboil the beef bones: Fill a large stockpot (about 12 quart capacity) with water and bring to rapid boil. Carefully lower in the bones. Wait until the water returns to a hard boil. Boil vigorously for 3 minutes to release the impurities. Dump bones and water into a clean sink, and rinse the bones with water to wash off any clinging residue. Quickly scrub pot clean and fill with about 6 quarts of clean water. Return bones to pot. Add the charred onion, ginger, spices, beef, fish sauce, and sugar to pot.

Step 3

Bring water to boil over high heat, and lower heat to gentle simmer. Simmer, uncovered, for 1 1/2 hours.

Step 4

While simmering, use a ladle or fine-mesh strainer to spoon off any scum that rises on top.

Step 5

At this point, the boneless meat should be slightly chewy, but not tough. Use tongs to transfer the meat to a bowl. Cover with plastic wrap and refrigerate. Meanwhile, maintain the broth at a steady simmer for 1 1/2 hours longer.

Step 6

Strain the broth through a fine-mesh sieve (or a coarse-mesh sieve lined with cheesecloth) positioned over a pot. Discard the remaining solids. Use ladle or fine meshed skimmer to skim as much fat as possible from the top of the broth. Taste and adjust the flavor with salt, fish sauce and sugar. There should be about 4 quarts (16 cups) of broth.

Step 7

If using dried rice noodles, cover them with hot tap water and let them soak for 15 minutes, or until they are pliable and opaque. Drain in a colander. If using fresh rice noodles, untangle them, place in a colander, and rinse briefly under cold running water.

Step 8

Cut the cooked beef across the grain into thin slices. Freeze the raw beef for 15 minutes, then slice it across the grain into very thin slices. Set all beef aside. Ready the raw onion, scallions, cilantro leaves for adding to the bowls. Arrange the garnishes on a plate and put on the table.

Step 9

To ensure good timing, bring the broth to a simmer over medium heat as you are assembling the bowls.

Step 10

At the same time, fill a separate large pot with water and boil. For each bowl, place a portion of the noodles on a strainer (or mesh sieve) and dunk the noodles in the boiling water for 10 seconds. Immediately pull the strainer from the water, letting the water drain back into the pot. Empty the noodles into a bowl.

Step 11

Top each bowl of noodles with cooked and raw beef, arranging the slices flat. Add a bit of raw onion, scallions, cilantro leaves to each bowl.

Step 12

The pho broth needs to be boiling hot, to cook the raw beef slices. Raise the heat of the broth to a boil. Do a final taste and make any last minute adjustments with fish sauce and sugar. Ladle about 2 cups of broth into each bowl. Serve immediately with plate of garnishes.