Fill a large pot with salted water and bring it to a boil. Cook the pasta until al dente, about 8-10 minutes, then drain and rinse under cold water to cool quickly.

If using fresh shrimp, add them to the boiling water and cook until they are pink, about 2-3 minutes. For pre-cooked shrimp, just chop them into bite-sized pieces.

Dice the imitation crab, celery, red bell pepper, and red onion into small pieces.

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

In a large bowl, mix the cooled pasta, shrimp, imitation crab, chopped vegetables, and the creamy dressing. Toss gently until everything is well coated.

Cover the bowl and refrigerate the salad for at least 1 hour. Garnish with fresh parsley and paprika before serving.