In Lima, you can buy bags of seafood mix, but if you have a hard time finding them, get a variety of clean seafood and combine it as you like.
This ceviche takes three ingredients not usually found in a Peruvian ceviche: olives, tomato and avocado. The combination is excellent and the flavors mix very well. But, since it’s all a matter of taste, you can omit any of them and the result will still be great.
The secret here is using the fast-cooking method for the seafood, so that the final product is very tender. Keep in mind that overcooking will cause it to get hard and that will ruin the dish.