Preheat the oven to 180 degrees C. Put the onions, carrots, celery and sweet potato in a large flameproof casserole dish. Pour in the stock and bring to the boil.
Add the garlic, leeks, pearl barley, sage and seasoning. Stir to mix the vegetables together. Cover and transfer to the oven to cook for about 1 hour or until the vegetables are just soft and the barley is tender.
Sprinkle with the parsley and serve. Thick slices of bread are an excellent accompaniment.
This is a mixed review. My husband loved it, but I found all the sweet potato made it a touch on the sweet side. I also found that, although the pearl barley was only just cooked, the sweet potato had disintegrated: I'll need to use much larger chunks next time. My 4 star rating is a combination of my hubby's rating with my own. Overall, a good hearty meal for winter. - 13 May 2009