The water was not boiling but it had begun to steam a little and I picked up the can with a rag and flung it at him, then took to my feet in frantic flight.

A less brilliant writer would have gone with something like "I picked up the can of hot water and flung it at him..." or even made the water actually boiling, for violent effect. But Portis/Mattie has a curious precision to her and a way of suckerpunching the reader, so we get that downplaying intro, "the water was not boiling". Until "I picked up the can", the sentence is playing out like no more than colour, background, as the conversation between Mattie and her captor (and object of her vengeance) Tom Chaney continues to play out. Then BAM, it hits us just the way it hits Chaney! I've always thought Tom and Jerry came out of the Wild West tradition, and screwball comedy, both artforms celebrating the terrible unpredictability of the frontier, and there's a lot of both in Portis. True Grit has a hell of a lot to say about America, and it's also a good time all the time and the definition of a one-sitting novel.

It's been a long time since I got such a visceral thrill from a sentence as from the last of these three:

I have never been very fond of horses myself although I believe I was accounted a good enough rider in my youth. I never was afraid of animals. I remember once I rode a mean goat through a plum thicket on a dare.