Bring a large pot of water to a boil. Salt the water, add the pasta, and cook until al dente. Reserve ½ cup of the pasta water, then drain the pasta.
8 ounces pasta, ½ reserved pasta water
While the pasta cooks, heat the olive oil in a large skillet over medium-low heat.
¼ cup olive oil
Add the garlic, red pepper flakes, salt, and black pepper. Cook for 1 minute, stirring often, until the garlic is fragrant.
3 garlic cloves, ½ teaspoon salt, ¼ teaspoon red pepper flakes, ¼ teaspoon black pepper
Add the drained tuna and chopped olives. Stir to combine and cook for 1 to 2 minutes, breaking up the tuna slightly as it warms.
2 (5 to 6-ounce cans) tuna packed in water, ¼ cup olives
Add the drained pasta and toss with the tuna mixture. Add reserved pasta water, 1 to 2 tablespoons at a time, until the sauce reaches the desired consistency.
Remove from heat and stir in the lemon zest and lemon juice. Serve immediately.
1 teaspoon lemon zest, 1 to 2 tablespoons lemon juice