Bring a medium pot of water up to a boil and drop in the corn. Cook for about 3 minutes, then remove and allow to cool completely. Once cool, use a knife to remove the kernels from the cob, then place them in a large mixing bowl. Add the red onion, jalapeño, tomatoes, lime juice and salt, then mix to combine.
Blot the barramundi fillets with paper towels to absorb any excess moisture. Use a very sharp knife to carefully remove the bloodline from the center of each fillet, then slice in half lengthwise. Thinly slice the barramundi crosswise, against the grain, and add to the bowl along with the cilantro. Toss to combine, then place in the refrigerator for 15-30 minutes, depending on your preferred level of “doneness.” Be sure to check the ceviche and give it a mix every so often. As the fish marinates in the lime juice it will develop more of a “cooked” texture, and will begin to deteriorate after a few hours.
While the ceviche is marinating, use a mandoline or sharp knife to thinly slice the plantain lengthwise into long strips. Heat about 1 inch of vegetable oil in a large saute pan with high sides over medium high heat. When the oil is hot, drop in a few slices of plantain at a time and fry until golden brown and crisp, turning over once if necessary. Transfer to paper towels to drain, then sprinkle with salt while still hot. Repeat with the remaining slices.
Serve the chilled ceviche with the plantain chips. Be sure to keep the ceviche cold, and consume within 3 hours of making.
*Partially frozen fish is easier to slice than fully defrosted, so plan accordingly if starting with frozen fish. Store bought plantain chips may be substituted for the fresh fried plantain chips if pressed for time. They just won’t have the same visual impact.