Potage Crème de Tomates et de Pommes de Terre

Melt the butter in a large saucepan over medium low heat. As soon as it melts, add the leeks and cook, stirring occasionally, until softened, about 5 minutes. Keep the heat moderate—you want the butter and leeks to remain pale in color. Meanwhile, cut the tomatoes in half through their equators, squeeze and shake out the seeds, then chop the pulp.

Stir in the tomatoes and cook, stirring occasionally, for 5 minutes; add the potatoes. Season with salt and pepper and add the stock. Bring the soup to a boil, then reduce the heat and simmer for 30 minutes.

Using a food mill, an immersion blender, or an upright blender, puree the mixture until smooth, working in batches if necessary. (In this as in every instance, take care when pureeing hot liquid; it’s best, if you have the time, to let the mixture cool to room temperature before pureeing.) Reheat the soup (or refrigerate for up to a day before reheating); stir in the cream and additional salt and pepper as needed. If the soup seems too thick, thin it with cream or water. Garnish with chervil and serve immediately.