This is slightly unusual; I don't make turnip soup often, but I had a couple of jumbo turnips lying around and thought they'd go well with nettle tops from the hedgerows near my place in Charmouth.
A couple of knobs of butter
The white of 1 leek, chopped and washed
500g turnip, peeled and roughly chopped
500ml vegetable stock
A couple of handfuls of nettle tops, washed
Salt and freshly ground black pepper
Melt the butter in a heavy saucepan and gently cook the leek and turnip for a few minutes with a lid on and stirring occasionally. Add the milk and vegetable stock, season and bring to the boil.
Simmer for about 15 minutes or until the turnips are tender, then stir in the nettles and remove from the heat.
Blend in a liquidiser until smooth and add a little more stock or milk if it's too thick.
Re-season if necessary; serve immediately. If you're making the soup in advance, cool it down quickly over iced water, otherwise it will lose its vibrant green colour.