Sweet Pea and Tuna Salad

4 cups short pasta, such as shells or orecchiette
1 1/2 cups frozen peas, thawed
1 stalk celery, chopped
1/2 red onion, chopped
1/2 cup roughly chopped fresh flat-leaf parsley
2 6-ounce cans tuna, drained
1/3 cup olive oil
1/4 cup red wine vinegar
1 teaspoon kosher salt
1/2 teaspoon Dijon mustard
1/4 teaspoon freshly ground black pepper
Directions

1Cook the pasta according to the package directions. Drain and rinse under cold running water.
2In a large bowl, combine the pasta, peas, celery, onion, parsley, and tuna.
3In a small bowl, whisk together the oil, vinegar, salt, mustard, and pepper. Pour over the salad and gently toss. Serve at room temperature or chilled.