Roast Beetroot Soup

I fed this to JP and my mother in law the other day and it went down a treat.  It is adapted from one of Sarah Raven's "Garden Cookbook".  The secret is first roasting the beetroot in the oven.

500 grms beetroot
2-3 large beetroot leaves or swiss chard
1.5  litres of veggie stock
olive oil
2 onions-chopped
3 leeks chopped
2 carrots-chopped
2 celery stick-chopped
2 garlic cloves-crushed
salt and pepper
sour cream or cream to serve
chopped tarragon to serve

Preheat oven to 180 degrees/gas mark 4.  Tear the leaves off the beetroot, but do not cut its roots off.  Scrub the roots clean and roast in the oven for an hour or so.  The beetroots are cooked when the skin looks wrinkled and can be easily pushed off.
If using chard, seperate the green part of the card from the stalks and shred the leaves-do the same of using beetroot leaves.  In a pan gently fry in the olive oil the onions, leeks, celery, chopped carrots and garlic, until soft.  Add the stock and greens and simmer for about 10 minutes.
Rub the skin off the beetroot and chop it up.  Add it to the pan and simmer another 5 minutes or so.
Blend using a hand held blender or in a food processor.  If necessary sieve or mouli the soup to remove any fibrous bits.
Add a little water if the soup is too thick.  Check the seasoning and serve either hot or cold, with a swirl of cream and a scattering of chopped tarragon.