Peruvian Ceviche

Begin by preparing red onion through slicing onion very thinly into half-moons. Place sliced red onion in bowl and cover with ice water bath. Let onion soak for 10 minutes to remove harsh bite and soften flavor. Drain onions thoroughly and pat dry with paper towels

While onions soak, prepare fish by checking fresh white fish fillets for any remaining bones and removing them with clean tweezers. Cut fish into 2cm cubes using very sharp knife. Place cubed fish in large glass or ceramic bowl

Prepare sweet potatoes by peeling and cutting sweet potato into 2cm thick rounds. Bring medium pot of salted water to boil over high heat. Add sweet potato rounds and boil for 12-15 minutes until tender when pierced with fork but not mushy. Drain and set aside

While sweet potatoes cook, prepare corn by bringing separate pot of water to boil. Add corn on the cob and boil for 8-10 minutes until kernels are tender. Drain and cut each ear into 3-4 round sections. Set aside

Add drained red onion, minced garlic, grated fresh ginger, aji amarillo paste, fine sea salt, and freshly ground black pepper to bowl with fish cubes. Pour fresh lime juice over everything to completely cover fish. Stir gently to combine all ingredients

Cover bowl with plastic wrap and refrigerate for 8-12 minutes until fish turns opaque and white throughout. Fish is "cooked" when it loses translucent appearance and becomes firm. Do not marinate longer than 15 minutes or fish becomes mushy

Remove bowl from refrigerator and add roughly chopped fresh cilantro. Stir gently to incorporate cilantro throughout ceviche. Taste and adjust seasoning by adding more fine sea salt or fresh lime juice if needed

Serve ceviche immediately in shallow bowls or on plates lined with lettuce leaves for serving if desired. Arrange sweet potato rounds and corn sections alongside ceviche. Spoon generous amount of citrus marinade (leche de tigre) over fish. Serve immediately while fish is still cold and firm