Drain the tuna in the can.
In a bowl mix tuna, mayonnaise, cilantro and juice from half a lime. Add salt to taste and stir it all together
Peel and chop the avocado before placing it in a bowl. Squeeze the remaining half of a lime over it and lightly mash the avocado leaving some chunks. Salt to taste.
On a plate make a layer with half of the avocado. Then layer half of the tuna on top of that. Finish it with a layer of fresh pico de gallo salsa..