When preparing dishes with raw fish, it is best to use previously frozen fish fillets to minimize the risk of parasitic infection. The only two fish that the FDA doesn’t recommend using frozen, are farm-raised salmon and Tuna. Follow this link for more background on consuming raw fish.
If left to soak too long in the citrus marinade, the fish will start to break down and become pasty so this is best prepare and served within a few hours.
Sweet potato might seem a strange addition but it is a traditional part of Peruvian ceviche.
Yield: About 10 3” Tostadas
12 oz. Mahi Mahi or other white fish, previously frozen and thawed
1 small sweet potato
½ cup orange juice
½ cup fresh lime juice
2 tablespoons Sherry vinegar
½ medium red onion, finely diced
1 fresh chile, (jalapeno, serrano, red chili) finely minced
2 tablespoons fresh cilantro, finely chopped
10 3” corn tortillas
Vegetable oil for frying
2 avocados, cut into thin slices
Dice the mahi-mahi into 1/4-inch dice and place into a non-reactive bowl (stainless steel, glass, or plastic) and sprinkle liberally with kosher salt. Toss gently and set in refrigerator so salt can pull juices from the fish and firm it up, about 10-15 minutes.
Peel and dice the sweet potato into ¼-inch dice. Place in a small skillet or saucepan with the orange juice. Bring to a simmer and cook until the sweet potato is tender.
Remove the bowl of fish from the refrigerator and add the lime juice, sherry vinegar, onion, chile, and cilantro. Mix to combine ingredients and return to the refrigerator for about 30 minutes, or until ready to serve.
While ceviche is resting, heat about 1” of oil in the bottom of a 10 or 12-inch cast iron skillet or other heavy pan or pot. Heat oil to 350 degrees. A sprinkle of flour should sizzle immediately when added to the hot oil. Fry the tortillas in the hot oil until crispy. Drain well and then place on absorbent towels while the remaining tortillas are fried. While tostada shells are warm, season with kosher salt.
Remove the pit from the avocado and slice lengthwise into thin slices. Remove skin from avocado slices and arrange the slices 3 or 4 per tostada shell in a spiral pattern.
Remove ceviche from the refrigerator and add the cooked sweet potato. Taste for seasoning, adjust salt and pepper if necessary. Using a slotted spoon, spoon a mound of ceviche on top of each tostada and serve immediately.