In a medium sized pot, bring salted water to a boil and add the rice. The water must submerge the rice entirely. Cook for 15 minutes or until soft (not overcooked) and drain all the water out. Let the rice fully cool off at room temperature;
Meantime, in a large mixing bowl add all the ingredients as follows:
Drain the oil from the tuna cans and with a fork, break it into pieces directly into the bowl; the reason of draining the oil out is that I prefer to dress my salad with the olive oil of my choice. You could buy the tuna in water but the one in oil tastes better;
In a small strainer, drain all the liquid from the corn can and rinse the corn; you will so eliminate the slimy preservatives. If you wish to save some of the corn you can do so using a container and adding regular water to it;
Add all the remaining ingredients (previously cut and drained of their original liquid or oil as much as possible), add the cooled rice on top, dress with the EVOO and Mayonnese and toss well.
Let cool in the fridge for 30/45 minutes.