Preheat large, nonstick sauté pan on medium-high 2–3 minutes. Coat fish with 1 tablespoon oil, season with salt, and place in pan (wash hands). Cook 6–8 minutes on each side until centers of fillets flake easily and are 145°F.
Chop cucumber and onion finely. Halve mango and avocado, scoop out flesh, and chop finely; combine with cucumbers and onions. Whisk ponzu sauce, lime juice, and remaining 2 tablespoons oil until well blended. Toss with cucumbers, onions, mango, and avocado; serve over fish.
Note: Always check fish for bones.
Other Preparation Methods
Grill: Preheat grill (or grill pan) on medium. Combine 3 tablespoons softened salted butter, 2 tablespoons sweet chili sauce, and ¼ cup sliced green onions. Season 4 (6 oz) corvina fish fillets with ½ teaspoon kosher salt and 1 tablespoon oil, then place on grill (wash hands); grill 6–7 minutes on each side until centers of fillet flake easily and are 145°F. Top with seasoned butter.