Bring a large pot of salted water to a boil.
Add your pasta and cook it according to the package instructions until it’s al dente.
While the pasta is cooking, drain and flake the canned tuna with a fork.
Dice the celery, and red onion if using.
Thaw corn if frozen, drain if canned.
In a small mixing bowl, whisk together the mayonnaise, sour cream, lemon juice, Dijon mustard, salt, pepper, and dill.
Taste the dressing and adjust the seasoning as needed.
In a large mixing bowl, add the cooked pasta, drained tuna, corn, celery, and red onion.
Pour the creamy dressing over the top and gently toss everything together until all the ingredients are evenly coated.
Cover the bowl with plastic wrap and refrigerate the pasta salad for at least 30 minutes to allow the flavors to meld together.