Roughly chop and bash all the parsley stems. Mince one-third of the parsley sprigs and reserve for the garnish. Roughly chop the remaining sprigs.
Melt the butter with the oil in a saucepan and add the chopped onion and potato. Stir and cook for a few minutes before adding the garlic and roughly chopped parsley sprigs and stems. Stir again to make sure the parsley is well coated with the butter and oil, then leave to cook over a low heat for 10-15 minutes, making sure the onions don’t brown.
Add the stock and some salt and pepper. Bring to a boil, then simmer for 15-20 minutes or until the potatoes and onions are very tender. Leave the soup to cool, then purée in a blender. Return to the saucepan and add the lemon juice. Reheat the soup and thin with the cream (the exact amount of cream will depend on the thickness of the soup). Adjust the seasoning, if necessary, and stir in the minced parsley.
© 1999 Jennifer Paterson and Clarissa Dickson Wright estate. All rights reserved.