Add the spice bag into the pot along with the scallion/spring onion knot. As the broth simmers, remember to skim the floating scum from the top every 30 minutes.
After 1 hour, season with the fish sauce, chicken bouillon powder, salt and sugar.
Ten minutes after adding the seasoning, take the brisket out and place into an ice bath for 10 minutes. This will slow down the cooking process and stop it from overcooking. When cool, thinly slice and let aside to use as a topping.
Scrub 3 tbsp salt through the bible tripe and tendons, then rinse clean. Repeat once more.
Add them into the broth to cook. Take the tripe out after 15 minutes or when just cooked. Let the tendon cook for a total of 3 hours or until soft in the Phở broth.
When cool, thinly slice and let aside to use as a topping.Note: If the brisket is still tough when you poke through it using a chopstick, let it simmer for another hour or until just beginning to soften. After another 2 hours, take the oxtail out and set aside to use as a topping. You can also scoop the onions out of the Phở broth at this point to prevent them from breaking and making the soup murky.Note: Oxtail will take about 3 hours to cook, so test its texture at the 2 hour mark. Leave it to simmer for longer if needed or remove immediately when soft.
Add the meatballs into the broth to heat up. Use scissors to cut the tripe into thin slices along the thicker part.
Once the tendons have been cooking for 3 hours or until soft, scoop them out and cut them into smaller segments, roughly 3cm (1.2") long. Set the tripe and tendons aside to add as a topping.