In Night by Elie Wiesel, why does Eli say,"I found the soup excellent that evening," after the first hanging?

In Elie Wiesel's book Night, he says, "I found the soup excellent," after he witnesses the Nazis hang a prisoner. He says this to show us how numb he has become to death and suffering. By this point in the book, Elie has witnessed so much horror that it has become normal for him.

He saw babies burned in a fire pit. He watched his father beaten by guards. He saw men shot for no reason, women and children sent to the gas chambers, and more. He has become immune to all of it. All he cares about now is his next bowl of soup or his next piece of bread. When one witnesses such terrible acts day after day, one begins to lose his/her own humanity, and this is where Elie was when he said those words.