1. Break matzo into about 6 pieces each and place in mixing bowl along with Vietnamese mint leaves. Blitz 9 sec/speed 6. Set aside. If not using a Thermomix, crumble in a food processor.
2. Insert Butterfly. Separate eggs and place egg whites in mixing bowl. Mix 1 min/speed 4. If not using a Thermomix, whisk egg whites to soft peaks by hand or in a mixer.
3. Add yolks, reserved matzo meal and salt. Mix 15 sec/speed 2. If not using a Thermomix, fold together gently in a mixing bowl. Set aside in a container and place in the refrigerator for at least 30 minutes (this can be done the day before). When firm, roll dessertspoonfuls of mixture into balls and place in Varoma. Remove Butterfly and clean mixing bowl. If not using a Thermomix, cook balls in simmering chicken broth.
4. Place 1.5L chicken broth in mixing bowl and set Varoma in place. Steam 20 min/Varoma/speed 2.
5. Remove Varoma and drop matzo balls into broth. Cook 2 min/100°C (212°F)/Rev/speed 1.
Serve hot, in shallow bowls.