Peel the onion, and cut in half. Peel the ginger. Put in a foil tray together with the spices group and in the toaster oven set to broil for around 20 minutes (flip over after 10 minutes). The onion should be slightly charred. When you can smell the grilled onion, keep an eye on it to prevent burning.
Put all the spices in a cheesecloth sachet. You may have to break the cinnamon stick.
Put the beef in colander, rub with the salt and rinse under running water
Slice the Daikon or white radish
Put the beef, onion, ginger, Daikon and spices sachet in the instant pot.
With a measuring cup, pour water in the instant pot up to the max. level (reserve the remaining water). Add the sugar, salt, fish sauce, beef cubes.
Lock the instant pot lid, set to high pressure cooking for 20 minutes. It will take around 20 minutes to reach pressure level. After 20 minutes cooking, allow for natural steam release for 20 minutes.
Blanch the rice noodles according to the package instructions, divide into 6 large soup bowls. Arrange the sliced raw beef filet in each bowl (the hot broth will blanch the filet).
Wash the herbs and bean sprouts, slice the limes and chilis, and arrange on a serving platter.
After cooking and steam release, cancel the pressure cook function. Remove the beef into a bowl. Discard the spices sachet, the Daikon and onion. Skim the fat that rises on top. Strain the broth through a sieve fitted with a muslin or cheesecloth into another pot or container. If you make the broth the day before, this step is not necessary. The next day the solidified fat will rise to the top of the broth and can easily be removed and discarded. When ready to serve, return the broth to the instant pot and set to Saute.Add the remaining water (total water around 18 cups). Adjust seasoning to taste When the broth is boiling, add the beef balls if using.
Thinly slice the brisket across the grain (if this is made the day before, the brisket could be refrigerated overnight, and would be easier to slice). Divide the brisket, oxtail and beef short ribs and beef balls (if used) among the 6 noodles bowls. Laddle the boiling hot soup in each bowl. Sprinkle the sliced onion and spring onion on top.
Serve with the fresh herb platter, hoisin and sri racha sauce for the guests to help themselves.