Place all ingredients into the slow cooker, except for the peas. Stir to combine everything and cover with the lid.
Cook on high for 3-4 hours, or on low for 6-7 hours. In the last 30 minutes of cooking, add the frozen peas and stir to mix into the stew. If you want to add the thickener, whisk it into the slow cooker at this time. Cover with the lid and let the peas heat through.
Add any additional salt to taste, and serve with additional chopped parsley if desired.