Put the rice vinegar together with the sugar and a pinch of salt to heat in a saucepan. Once hot, pour over pre-cooked sushi rice and stir very gently to soak thoroughly.
In another bowl, put some water with a teaspoon of rice vinegar to wet your hands and work the rice with ease. Take the rice with clean hands and shape until it is compact.
Once you have shaped all the nigiri, place a shrimp cut down the middle on top. Place a teaspoon of Salmón Shikrán or Ojos de Neptuno on top of each, alternating them.
Serve with some soy sauce for the nigiri.
