To ensure creamy, well-seasoned lentils with intact skins, we soak them in a warm brine for 30 minutes before cooking. For a rich, vegetal flavor, we sweat onion, carrot, and parsley in a covered pot to provide a background taste to the main ingredients: heady smoked paprika, meaty chorizo, earthy lentils, and tart sherry vinegar. To finish the soup, we garnish it with an Indian preparation called a tarka, a mixture of spices and aromatics bloomed in oil.