Make the pickled onions: In a small saucepan, bring the vinegar, sugar, and chiles to a boil. Stir until sugar is dissolved. Remove from heat. In a plastic container, place the sliced onions and pour the liquid over them. Place the container in an ice bath to cool. Store in refrigerator until ready to use.
Island Ceviche with Pickled Onions
Cut the fish into pieces resembling the size of the scallops. Separately toss the seafood with a little oil and season to taste with salt and pepper.
In a saute pan over high heat, sear the fish and scallops, about 30 seconds on each side. The middle should still be raw. Work in batches so you don't overcrowd the pan. Place seafood into a glass dish and coat with lime juice. Glass is best, as it won't react with the acid in the juice. Marinate, refrigerated, overnight.
The next day, remove the flesh from half the papaya and cut into medium dice. Slice the remaining half into long strips.
Pour the lime juice off the fish. Gently fold the drained fish and scallop mixture with the remaining ingredients and diced papaya. Serve with tortilla chips, sliced papaya, and Pink Pickled Onions.