Heat oil in large saucepan over medium heat. Add leeks, onion, carrots, and pinch of salt; cover and cook 5 to 7 minutes, or until vegetables are softened, stirring often.Stir in broth. Season with salt and pepper. Cover, reduce heat to medium-low, and simmer 10 minutes. Add orzo, and cook 11 minutes more, or until orzo is tender. Remove from heat.Whisk together eggs and lemon juice in bowl. Add 3 ladles soup broth to egg mixture, whisking constantly. Whisk egg mixture back into soup, and cook over low heat 2 to 3 minutes, or until soup is thickened, but without letting it come to a boil. Serve sprinkled with parsley, mint, and oregano, and garnished with lemon wedges.