For dressing, combine celery, green onions, garlic, mayonnaise, yellow mustard, white vinegar, pickle relish, Old Bay, smoked paprika, and onion powder in a bowl. Whisk until smooth. Stir in scallions. Season with salt and pepper. Refrigerate.
STEP 2
For the salad, fill a large pot with water, lemons, garlic cloves, and Old Bay seasoning. Bring to a boil.
STEP 3
Add potatoes and boil for 10 minutes. Then add eggs and shrimp. Turn off heat, cover, and let sit for 10 minutes.
STEP 4
Remove shrimp, potatoes, and eggs to cool. Peel eggs when cool enough. Set aside.
STEP 5
Stir potatoes into dressing. Break peeled eggs into the potato mixture and stir. Add shrimp. Wrap and refrigerate until serving.