Chop and prepare the vegetables.
Place the vegetables, barley (or gluten-free grain), and seasonings into a large slow cooker. Add enough vegetable broth to just cover the vegetables. This should be about six cups of vegetable broth, but you can add more if necessary.
Cover and cook on low heat for seven hours.
Add the beans, tomatoes, parsley, and salt to taste.
Check the seasonings and add more herbs if desired.
Cover and cook for one more hour.
Serve immediately.