Combine onions, lime juice and celery in a bowl. Add flaked tuna, chopped aji, blended aji and mix well. Season with salt and pepper and set aside for 30 minutes.
Arrange on a serving dish, sprinkle with chopped parsley and cilantro and garnish with lettuce leaves. Serve with corn and slices of cooked yellow sweet potato.
How to fillet, skin and debone fish