 The marinade ingredients include salt, lime, onion, chili peppers, avocado, and cilantro (coriander).Cut olives and a bit of tomatoes are often added to the preparation (ketchup is not used because it adds sugar and is not fresh).In El Salvador and Nicaragua one popular ceviche recipe is "ceviche de concha negra" ("black conch ceviche"), known in Mexico as "pata de mula" ("mule's foot").