Put the chitterlings in a large pot along with your 3 quarts water, onion, pepper, and salt.
Boil them for 1 1/2 hours or until tender. Add a little extra water if necessary.
Prepare a large cast iron skillet with 1/4 stick of butter. Remove chitterlings from pot and slice.
Add to the preheated skillet. Stir as you lightly brown them.
The chitterlings should be thoroughly done and almost falling apart. You can serve them with your favorite side dishes such as greens, maccaroni and cheese, or rice. I actually prefer to eat them by themselves, with several splashes of hot sauce.