In a large saucepan, melt the butter over medium-low heat. Add the leeks and cook, stirring occasionally, for 10 minutes, or until tender.
Add the lettuce and mint and cook for 5 minutes, stirring occasionally, until the lettuce is very tender.
Stir in the peas, salt, and pepper and stir to combine. Add the broth and bring to a boil. Reduce to a simmer, cover, and cook for 5 minutes, or until the peas are tender and the flavors have blended.
Working in 2 batches, transfer the soup to a blender and puree until smooth. Add the cream and lemon juice and blend. Serve hot.
TIDBIT: To get 2 cups of shelled peas, you'll need to start with about 2 pounds of peas in the pod, so feel free to use frozen peas here (we'll never tell).
Reprinted from “The Beekman 1802 Heirloom Vegetable Cookbook” by Brent Ridge and Josh Kilmer-Purcell. Copyright (c) 2014 by Beekman 1802, LLC. By permission of Rodale Books. Available wherever books are sold.