Creamy Hungarian Mushroom Soup

Name: Creamy Hungarian Mushroom Soup
Ingredients: 3/4 cup sour cream, plus more for serving; 1/2 medium lemon; 2 medium yellow onions; 1 pound white button or cremini mushrooms, or a combination; 4 cloves garlic; 1/2 medium bunch fresh dill; 1/2 bunch fresh thyme leaves; 2 teaspoons Hungarian sweet or hot paprika; 4 tablespoons (1/2 stick) unsalted butter; 1 teaspoon kosher salt; 1/2 cup dry white wine; 3 cups low-sodium chicken or vegetable broth; 2 tablespoons Worcestershire sauce; 1 cup whole milk; 2 tablespoons all-purpose flour