Francesca Rios, the chef/owner of Los Cabos, gave me this classic Peruvian recipe just in time for the beginning of potato season, when tiny, sweet marble potatoes are readily available. Huancaina is a rich, spicy, smoky sauce made with yellow Peruvian chiles, cheese, evaporated milk and thickened with crackers. Traditionally, Huancaina sauce is served over room-temperature boiled potatoes and garnished with hard-boiled eggs, black olives, red aji chiles and a few lettuce leaves.