Bring a large pot of salted water to a boil. Cook capellini for 3 to 5 minutes until al dente, then drain and rinse under cool water.

In a mixing bowl, whisk together the lemon juice, olive oil, garlic salt, and black pepper until emulsified.

Add the cooled pasta, diced tomatoes, and capers to the bowl. Toss gently to coat evenly.

Add chopped parsley and lemon zest, toss again to combine.

Serve immediately, or chill in the refrigerator for 30 minutes before serving.