Cook the pasta: Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Rinse briefly under cold water to stop the cooking process, then drain well and set aside.
Make the dressing: In a small pan, heat the olive oil over medium-low heat. Add the garlic and cook gently for 2–3 minutes, until fragrant and golden. Stir in the chili flakes, then remove from heat. Let cool slightly before adding the lemon zest and juice.
Combine: In a large serving bowl, toss the pasta with the garlic-lemon oil and season with salt. Add the onion, roasted peppers, sun-dried tomatoes, olives, capers, tuna chunks, arugula, and basil. Toss gently until everything is evenly combined.
Finish: If desired, drizzle with extra olive oil and adjust the seasoning to taste. Serve and enjoy!
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