First prepare the green bell peppers. Cut off the tops and put them aside for later. Remove all the seeds and membranes.
Put the remaining ingredients EXCEPT the chicken stock in a large bowl. Mix together well, breaking up the ground beef and pork. Using your hands is the best way here to make sure everything is combined well.
Fill the peppers with the meat mixture. Place the 'tops' back on put into the slow cooker. The peppers should be over-flowing with the meat mixture, so the top will sit on top of the mixture. It won't fit down all the way.
Pour the chicken stock into the slow cooker around the base of the peppers.
Set to LOW, cover and cook for 7 to 8 hours, or until peppers are tender and meat is cooked.
Any color peppers can be used- green, red or yellow.
Different ground meats could also be used. Try chicken, turkey, veal.