Lovage is one of those herbs that you have to treat with extreme caution – something that will become obvious when you taste a raw leaf. The flavour can be very strong, and once you've added too much lovage, there's no going back; heavy-handedness can ruin a good soup.
You can serve this soup hot or cold; just use oil instead of butter for cooking the leek and onion if you're planning on making a chilled soup (otherwise the fat from the butter solidifies).
1 leek, roughly chopped and washed
1 onion, peeled and roughly chopped
50g butter or vegetable or corn oil (see above)
1.5 litres vegetable stock
300g podded weight of fresh or frozen peas
A couple of sprigs of lovage
Salt and freshly ground black pepper
4 rashers of rindless streaky bacon
Gently cook the leek and onion in the butter (or oil) until soft. Add the vegetable stock, season with salt and pepper and simmer for 20 minutes. Add the peas (reserving a few for garnish) and the lovage, bring back to the boil and simmer for 6-7 minutes.
Blend the soup in a liquidiser until smooth and strain through a fine-meshed sieve. Correct the seasoning if necessary. While the soup is cooking either fry or grill the bacon until crisp, leave to cool and chop it finely.
If you are serving the soup cold, then chill the warm liquid as quickly as possible on some ice so that it retains its vibrant green colour.
Serve with a few cooked peas in the soup and scatter with the bacon.