Place ¼ of the diced mango in the blender together with lime juice and pepper. Blend until creamy. Season with salt, aji and chopped cilantro.
Combine this cream with the diced mango in a bowl. Add onion and mix. Refrigerate.
Place lettuce leaves on dishes or a martini glass, season with salt and drizzle oil. Arrange mango ceviche on top of lettuce. Sprinkle some finely chopped aji limo and decorate with a cilantro sprig.