Cook the pasta in boiling salted water until al dente, about 8-10 minutes, then drain and rinse under cold water.

If using fresh shrimp, cook them in boiling water for 2-3 minutes until pink. Drain, cool, and chop.

Chop celery, red bell pepper, and red onion to similar sizes. Add parsley for garnish.

In a bowl, mix mayonnaise, sour cream, Dijon mustard, and lemon juice. Add Old Bay seasoning, salt, and pepper. Whisk until smooth.

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

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

Toss before serving and serve on a bed of lettuce. Garnish with parsley and optional paprika.