Boil a salted pot of water for your pasta and cook it al dente according to package directions. Prep your other ingredients while it cooks.
When the pasta is close to being ready, add the oil to a small pan over medium heat. Once the oil is hot, add the garlic and cook it for 30 seconds.
Stir in the tuna, lemon juice, and parsley. Let it heat through.
Once the pasta is done, add some of the pasta water (a couple tablespoons) to the sauce and then drain the pasta and toss with the sauce. Season with salt & pepper as needed. Optional: serve pasta with freshly grated parmesan cheese and lemon zest.