Boil the shell pasta, according to package directions, about 7 minutes.
1 pound medium shell pasta
Drain and rinse well with cold water.
Add the pasta to the bowl, and add tuna, peas, celery, and onion.
10 ounces white albacore tuna in water, 1 ½ cups frozen peas, 2 celery stalks, ½ small red onion
Toss all of the ingredients together.
In a separate bowl, whisk together mayonnaise, green yogurt, dill, and salt and pepper.
1 cup mayonnaise, ½ cup plain greek yogurt, 1 teaspoon dried dill, salt and pepper
Pour the dressing over the salad and toss again, until well coated and combined.
Cover and let the salad chill in the refrigerator for at least two hours.