Add beef brisket in a wok. Cover it with water. Turn the heat to medium. Bring the water to boil. Blanch the beef for 5 mins. Rinse it well and put it aside.
Heat the pan with 1 tsp of oil. Stir fry the garlic, ginger and green onion until you smell the fragrance
Instant pot step
Add garlic, green onion, ginger, beef brisket and spice mixture in instant pot. Add water to cover the beef. Set it to pressure cook for 30 mins (adjust it if you using different brand and machine)
Stovetop step
Add garlic, green onion, ginger, beef brisket and spice mixture in a wok. Add water to cover the beef. Bring the water to boil over high heat. Cover and simmer it over high heat for 5 mins. Turn the heat to low. Continue to cook for 30 mins. Repeat the same step once until the beef is tender
Rest of steps
Remove the beef and put it aside. Let it cool down and slice it. Drain the broth through a sieve. Remove the oil from the broth. And only keep 300 ml of it.
In a clay pot, add in the reserved beef broth, chicken broth, diced coriander, green onion, and white radish. Bring the broth to boil over high heat. Cover with a lid. Turn the heat to medium and simmer for 20 mins
Add some fish sauce to taste. Then add back the beef brisket. Bring the broth to boil over high heat. Cover with a lid and simmer for 5 mins. Enjoy