Make the meat-mash

• Portion out 2 cups of the stock in a bowl and sprinkle with the dry gelatin. Allow it to sit while you complete a few more steps. The gelatin will absorb the cool liquid, a process called “blooming.”

• Meanwhile, combine the chicken chunks and chuck chunks with the egg white in a bowl, mix to combine.

• Run the meat mixture through your food processor in small batches. (The chicken bones should not harm the blade or the processor. If your processor is weak or fragile, just grind the beef with the egg white and combine it with the shear-cut chicken wings.) Pulse each batch 12–15 times for 1 second each pulse. The result will look a lot like ground beef, but with little shards of chicken bone in it.

Make the broth

• Tie the spices in a small packet of cheesecloth.

• Heat the tablespoon of oil in a large, heavy-bottomed pot. When it is smoking hot, place the onions and the ginger pieces, cut-side down, in the oil, and cook until they char, 3–5 minutes.
• Turn the onions and ginger over and cook for a few minutes on their backs until they start to char.

• Add the stock/gelatin mixture, the rest of the stock, the fish sauce, one of the pieces of flank steak, the spice packet, and the sugar to the pot. Bring to a boil.

• Reduce the heat to a simmer and stir in the meat-paste mixture. As that mixture cooks, it will rise to the top. This is called a raft. Do not break it up.

• Allow the broth to simmer up through the raft, depositing impurities on top and becoming more clear.
• Simmer slowly for 45 minutes, uncovered.

Strain broth and prepare for service

• Once the broth is well infused and you just can’t stand how delicious it smells without eating it any longer, use a slotted spoon to remove the raft from the pot. Fish out the spice packet and the onions.
• Pour the broth through a fine-mesh sieve or a few layers of cheesecloth into another pot.

• Remove the piece of cooked flank steak and cut it into cubes to divide among the bowls.
• Keep the broth warm over a low flame until you’re ready to serve.

• Slice the remaining (raw) flank steak thinly across the grain. Portion it into four large bowls.

• Take the temperature of your broth with your Thermapen ONE. It should be in the neighborhood of 200°F (93°C).
• Ladle the hot broth over the raw meat in one of the soup bowls. Stir it for a moment, then take the temperature of the broth and the meat again with your Thermapen. The meat should be at least 130°F (57°C), medium-rare. If you like the doneness of the meat, ladle the broth into the other bowls. If you want it more or less done, heat or cool the broth more before ladling it into the other bowls.
• Add the prepared rice noodles to the bowls and serve!

• Let each person add torn herbs, lime juice, chilies, bean sprouts, and all the other toppings themselves.