Persian Leek Frittata with Yogurt Sauce and Curried Walnuts

Name: Persian Leek Frittata with Yogurt Sauce and Curried Walnuts
Ingredients: Leek and Herb Frittata; 3 leeks (large), white and light green parts; 1 bunch parsley; 1 bunch cilantro; 4 garlic cloves, minced; 8 eggs, beaten; 1 teaspoon salt; 1 pinch cayenne pepper (optional); 1-2 tablespoons butter or oil; Yogurt Sauce and Curried Walnuts; 1 cup plain yogurt; 1 orange, zested and juiced; 1 tablespoon honey; 1 cup walnut halves or pieces; 1 teaspoon brown sugar; 1 tablespoon curry powder