Put the olive oil and the diced onions in the bottom of the slow cooker. Turn it to high, and let the onions warm in the oil for about five minutes.
Add all of the other ingredients EXCEPT the pinto beans, salt, and pepper. Make sure all of the rice is covered with liquid.
Cover and cook on high for three hours.
After three hours, remove the lid and add the beans, salt, and pepper. Stir. If it looks like it needs a little more liquid, add some room temperature water and stir. (You should never add cold liquids to a hot crock pot).
Cover again and cook for another hour.
Add more salt and pepper if needed. Serve with cornbread.