A patient suffering from cirrhosis
should be given food that is free from oil. Boiled and blanced food is the best. You are correct, liver
is the main organ of the body, it should be given minimum load to help the patient recover faster. You did not specify since when your friend is ill. Light food would be the best for him.
Boiled papaya, sugarcane juice are natural form of liver tonic. I will suggest you to consult a nutritionist who can talk with the treating doctor, see his treatment chart and investigations and plan a proper diet chart so that you can be confident about your friends diet.