Bring a large pot of salted water to a boil. Add pasta and cook for 7-9 minutes until al dente. Drain and rinse under cold water.

If using fresh shrimp, boil in another pot for 2-3 minutes until pink and opaque. If using pre-cooked shrimp, chop into pieces. Let shrimp cool.

Finely dice celery, red bell pepper, and red onion. Chop fresh parsley and set aside.

In a mixing bowl, whisk together mayonnaise, sour cream, Dijon mustard, lemon juice, Old Bay seasoning, salt, and pepper until smooth.

In a large bowl, combine cooled pasta, shrimp, imitation crab, and chopped vegetables. Pour dressing over and toss gently.

Cover and refrigerate for at least 1 hour to allow flavors to meld.

Before serving, give a gentle stir and garnish with parsley and optional paprika.