Autumn Lamb and Vegetable Stew

Name: Autumn Lamb and Vegetable Stew
Ingredients: 1 lemon, halved; 4 medium artichokes; 1/4 cup extra-virgin olive oil; 4 garlic cloves, halved; 2 leeks, white and tender green parts only, halved lengthwise and cut crosswise into 2-inch lengths; 2 celery ribs, cut into 2-inch lengths; 2 small fennel bulbs, quartered; 1 quart water; Salt; 1/4 pound green beans, cut into 2-inch lengths; 1 1/2 pounds boneless leg of lamb, cut into 1 1/2-inch pieces; Freshly ground pepper; 2 teaspoons sweet pimentón (see Note); 2 tablespoons all-purpose flour; 1/2 cup dry white wine, preferably Rioja