1 (5.6-ounce) Imported Italian Tuna, packed in olive oil, reserve the oil
In a large pot, boil the potatoes, skins on, with enough water to cover them by 2 inches. Once boiling, lower the heat to medium and continue simmering until the potatoes are easily pierced with a sharp knife, about 20 minutes. Drain and cool. Peel.
Cut the potatoes into 3/4-inch cubes and place into a large mixing bowl. Add the remaining ingredients, except the tuna. Turn gently to coat and mix evenly. Add the tuna, without draining oil, and gently toss to incorporate.
Refrigerate for 1 hour to chill if you prefer, or you can also serve slightly warm, where the flavors seem much more buttery.