Cook the pasta according to package instructions until al dente. Drain and rinse under cold water to cool.

In a large mixing bowl, combine the cooked pasta, drained tuna, cherry tomatoes, cucumber, red onion, bell pepper, and black olives.

In a small bowl, whisk together the mayonnaise, lemon juice, Dijon mustard, salt, and pepper.

Pour the dressing over the pasta mixture and toss gently to combine. Garnish with chopped parsley and serve chilled.