Go to the mission "Tastes Like Chicken".

Antonio will try and whack you with a pan. He will also throw plates towards you. Dodge them!

When he eats, whack the shit out of him with either a Katana, Light Sword, Boxing Knives or Broom/Machete.

This should drain his health very quickly.

When he is eating he only gets a little health so it's possible to kill him!