Rinse and sort dried pinto beans removing any debris. Place the beans in a 7-8 quart soup pot and cover with cold water by at least one inch. Cover with a lid and soak overnight.
When ready to cook, drain and lightly rinse the beans and place back in the pan. Cover with fresh water by at least two inches. Heat on medium and bring to a boil. Lower heat to maintain a simmer and cook until the beans are tender, but not soft; about 45 minutes. Add water if needed during cooking to keep most beans covered.
Add the canned diced tomatoes and cover the pot with a tight fitting lid, and reduce the heat to low.
In a large skillet, warm the vegetable oil over medium heat. Once shimmering, add the green peppers and sauté for five minutes. Add the onion and cook until tender, stirring often. Push the peppers and onions aside making a hole in the center of the pan. Add the minced garlic and sauté for 30 seconds. Pour the pepper mixture into the beans and add the parsley.
Return the skillet to the heat and add the butter. Once melted add the ground beef and pork and cook, breaking the meat into large chunks until cooked through.
Quickly drain the meat in a colander (don't leave it to dry out) and return it to the skillet. Add the chili powder and sauté for about five minutes or until all the meat is coated in the spice.
Add the cooked meat to the pot with the beans along with the salt, pepper, cumin, seasoned salt, cayenne and tomato paste. At this point you can add a little water if you think it needs it to ensure all ingredients are wet.
Cover and simmer (do not boil) chili for 1 hour, stir occasionally taking care not to smash the beans.
Remove the lid and simmer for 30 minutes.
Serve garnished with sliced green onions and shredded cheese if desired.