While you are prepping the ingredients, cook the pasta according to directions. When you drain it, reserve ¼ cup of the pasta water.
Zest the orange. Then using a pairing knife, remove the rest of the peel and pith. Cut the flesh into bite sized sections and set aside with the zest.
Add the olive oil to a skillet over medium-high heat. Add the onion and garlic to the pan, stirring until the often has softened and the garlic is fragrant about a minute or two.
Add the tuna, zest and orange flesh, raisins and capers. Toss this all together for a couple of minutes to warm it up. Add the pasta to the skillet along with about ½ of the reserved pasta water and half of the parsley. Toss to coat. Add salt and pepper to taste. If it’s too dry add more of the pasta water.
Serve on warmed plates and garnish with the rest of the parsley.
Video
Notes
I have made this with oil packed tuna and without, either one is fine. Oil packed has more flavor, but I can't always find it at the store.