Creamy Nettle and Potato Soup

Name: Creamy Nettle and Potato Soup
Ingredients: 6 tablespoons unsalted butter; 4 medium shallots (coarsely chopped); 4 celery ribs (coarsely chopped); 1 large leek (white and tender green parts only, halved lengthwise and thinly sliced); 1 ¼ pounds Yukon Gold potatoes (peeled and cut into 1/4-inch dice); ¼ cup dry white wine; 1 tablespoon fresh lemon juice; 4 ¼ cups water; Bouqet garni (made with 1 thyme sprig, 1 tarragon sprig and 1 bay leaf, tied with kitchen string); ½ cup heavy cream; 10 ounces nettles or spinach or 1 bunch flat-leaf parsley and 1 bunch (4 ) sorrel (5 stems and tough ribs removed); Salt and freshly ground white pepper