Open two cans of tuna. Drain as much of the liquid as possible.
Add all the ingredients in a large container. Even the carrots from the pickled jalapeños were used for texture. This is totally optional.
Add the olive oil, vinegar, and oregano to a separate bowl. Whisk to combine.
Pour the vinaigrette over the tuna and mix to combine.
Serve with tostadas and your choice of side dishes. This has to be one of the easiest recipes ever!