c("In a large, heavy-bottomed saucepan, heat the butter and olive oil over medium", "heat. Add the chopped onion, reduce heat  to low heat and cook slowly until the  onion are translucent.  Meanwhile, roll the sorrel leaves into a tight bunch  and, with a very sharp knife, slice into fine strips (julienne). Set aside half  the leaves.", "Add the other half to the pot with the onions, sprinkle the flour  and salt over them and stir to combine. Increase the heat to medium and cook for a few minutes until the sorrel are wilted.", 
"Gradually whisk in the hot stock and  let simmer for a further 10 minutes.", "Pour the soup into a blender and puree  until smooth.", "Add half the reserved sorrel leaves to the soup and puree again.", "Taste and season with pepper and more salt if needed.return to the saucepan aver low heat.  In a small bowl, whisk together the egg yolks and cream.", "Stir about a cup of hot soup into the cream mixture and gradually whisk it all back into the  pot. Stir in the mixture over medium heat for a few minutes until the soup  thickens slightly.", 
"Do not let it come to a boil or the yolks will curdle.  To  serve, divide the remaining sorrel leaves into 4 deep bowls.", "Pour a ladle of  soup over the leaves.", "Drizzle some olive oil on to the soup and serve  immediately.", "-----")