Crush the tomatoes with your hands and add to the slow cooker with all the juices. Add the remaining soup ingredients to the slow cooker (except the kale). Stir.
Cook on low for 8 hours.
Remove the parmesan rind and bay leaf, and stir in the chopped kale. Continue cooking for 10 minutes.
Serve topped with parmesan cheese and with whole grain bread.
Notes
This soup is best served with a hearty bread, don't forget to pick up some!
Leftovers freeze very well; pour any remaining soup into an airtight container and keep in the fridge for up to one week. Reheat on the stovetop over medium heat until warmed throughout.
To make this soup vegan, simply skip the parmesan cheese.