Put ox tail meat in a ceramic slow cooker.
Add in water and slow cooked on high for 5 hours and 7 hours on low.
When meat is ready, separate the soup and ox tail.
Saute' onion in a deep frying pan and then add the soup. Let it simmer and add the egg plant. Continue cooking until egg plant is tender.
Add in the peanut butter and mix to blend the soup and the peanut butter.
Add in fish sauce. Start with 1 tablespoon and add more if you want it to be saltier. The 2 tablespoons was good enough for me.
Simmer for 1 more minute and add in the ox tail meat and the bok choy leaves. Cook for 4 more minutes and serve hot with shrimp paste.
