Bring salt water to a boil in a large pan and boil the rice for about 15 minutes (if the rice is brown the cooking time will lengthen). In the meantime, peel the pink grapefruit and cut into cubes, cut the avocado into cubes and drain the precooked shrimps from the brine, rinsing well with cold running water.
Once the rice has been cooked, drain it and cool it quickly in pre-cooled Freddy with the function of blast chilling (it is recommended to spread the rice on a stainless steel pan in order to decrease the cooling time). Season the rice with a little oil, shrimp, avocado and pink grapefruit.