In a pot, boil the ox's bat and balls in 5 cups of water for 10 mins.
After 10 mins, remove the bat and ball from the pot and clean it up. Remove the black dirt from the meat.
Then, put it again in the pot and pour in addition 5 cups of water.
Then, add the sibot and lemongrass. Bring to boil. Lower the heat once it's boiling already. Simmer for 3 1/2 hours.
After 3 1/2 hours remove the pot from the fire.
Cut the bat and balls into 1 inch round pieces.
Heat oil in a pot, saute garlic until golden brown. Then add the onion and saute until softened.
Now, toss in the ginger. Mix well.
Now, add the bat and balls. Season with fish sauce and ground black pepper.
Pour in the beef broth. Filter the bat and balls broth and pour into the pot. Simmer for 20 minutes.
Add the sugar and simmer for 1 minute.
Ladle soup and meat into serving bowls.
Serve with scallions and enjoy!