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

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

In a separate bowl, whisk together mayonnaise, olive oil, lemon juice, dijon mustard, salt, and black pepper.

Pour the dressing over the pasta mixture and toss to combine. Stir in the chopped parsley. Serve chilled or at room temperature.