Hassan defiantly pointing his slingshot to Assef when he and his buddies are about to hit Amir. Even Assef's friends cannot help to admire his bravery.
Baba standing up to the soldier who tries to extort sex from one of the female truck passengers, holding him off long enough for the commanding officer to intervene.
When Amir stands up for Sohrab in front of his father-in-law, basically telling him to shut up with a twinge of Papa Wolf. It's even better because he bluntly reveals his kinship with Sohrab and Hassan, a thing that even his father couldn't do.
Sohrab pulling the slingshot on Assef and then hitting him in the eye. In the same eye Hassan threatened to hit all those years ago.