Bring a large pot of generously salted water to a boil. Add the rotini pasta and cook 1 minute past al dente according to package directions.

Drain the pasta and immediately rinse it under cold running water to stop the cooking process and remove excess starch. Drain well and transfer to a large mixing bowl.

To the cooled pasta, add the chopped imitation crab meat, chopped hard-boiled eggs, diced celery, and diced red onion.

In a separate medium bowl, whisk together the mayonnaise, sour cream, fresh dill, parsley, lemon juice, Dijon mustard, Old Bay seasoning, salt, and black pepper until completely smooth.

Pour the dressing over the pasta mixture. Using a large rubber spatula, gently fold everything together until all ingredients are evenly coated.

Cover the bowl tightly with plastic wrap and refrigerate for at least 2 hours to let the flavors meld.

Before serving, give the salad a gentle toss. If it seems dry, stir in a splash of milk or a spoonful of mayonnaise. Garnish with extra fresh dill and serve cold.