Brown the sausages at the bottom of the slow cooker's pan on a hob - by frying them for 1-2 minutes on each side. Take off the heat, remove any excess fat, and set the sausages on a side. (Go straight to step 2 if not browning sausages).
Wash, and dice all of the vegetables, peel and roughly chop the onion and put everything into the pan of the slow cooker.
Cover with chopped tomatoes, tomato puree, and stock. Season with herbs, salt and pepper and stir gently.
Halve the sausages and add them to the sauce (browned or raw), mix slightly, to ensure eveyrthing is covered or touching the sauce. Cover with a lid and cook for 6 hours on low or 3 hours on high setting.
After 6 hours (3 hours respectively), add pearl barley, stir, cover and cook for 50-60 minutes.
Add (frozen) garden peas, cover with a lid and cook for 10 minutes.
Check the barley is soft and serve with a slice of crusty buttered bread.
Notes
Top Tips
Keep the lid on throughout the cooking process.
Make sure there is enough liquid in the slow cooker. Add water if needed to prevent the sauce and sausages from drying out and burning.