Halve the white onion and ginger. Place them on an ungreased tray in the top rack of the oven to broil at 220°C for 15-20 minutes or until you see the outer layer beginning to turn charred and black.
Soak the noodles in water for 20-30 minutes until soft and bendable. Boil for ten minutes until they reache your desired consistency.
Pour the stock into a stockpot. Bring to a boil then simmer for 40 minutes. Remove any scum that floats to the top.
Prepare the beef by cutting into thin slices.
Add the fish sauce, place the garnishes on top and enjoy.