Step 1

Place the carrot, celery, onion, potato, sweet potato, garlic, rosemary, stock, diced tomatoes, barley and 500ml (2 cups) water in a slow cooker. Stir well to combine.

Step 2

Cook, covered, on LOW, for 6 hours (or HIGH for 3 hours), or until vegetables are tender and barley is cooked, adding the zucchini for the last hour of cooking time (see note).

Step 3

Stir the lemon juice into soup. Season. Serve soup sprinkled with parsley.