Cook the Pasta: Bring a large pot of salted water to a rolling boil. Add small pasta shapes, cook until al dente (8-10 minutes), drain, and rinse with cold water.

Prepare the Seafood: Cook fresh shrimp in simmering water for 2-3 minutes until pink, or chop pre-cooked shrimp and imitation crab.

Chop the Vegetables: Finely dice celery, red bell pepper, and red onion for balanced flavor. Optionally, chop parsley for garnish.

Make the Dressing: In a bowl, combine mayonnaise, sour cream, Dijon mustard, lemon juice, Old Bay seasoning, salt, and pepper. Whisk until smooth.

Combine Everything: In a large bowl, mix cooled pasta with shrimp, imitation crab, vegetables, and dressing. Toss until well-coated.

Chill Before Serving: Cover and refrigerate for at least one hour before serving. Garnish with chopped parsley and paprika if desired.