In a large bowl, combine the shrimp with baking soda, kosher salt, and Old Bay seasoning. Allow them to sit for 15 to 20 minutes.

While the shrimp brine, fill a large bowl with ice and cold water. Set aside for later.

Bring 8 cups of water to a rolling boil in a large pot and stir in 1 tablespoon of lemon juice. Add the brined shrimp and cook for 90 seconds.

Immediately transfer the poached shrimp to the ice water bath using a slotted spoon. Let them sit for about 2-3 minutes.

In a medium bowl, mix diced celery, finely chopped red onion, dill, mayonnaise, additional Old Bay seasoning, celery seed, and lemon juice. Add Dijon mustard, salt, and pepper.

Gently fold the cooled shrimp into the prepared dressing, ensuring each shrimp is evenly coated.

Cover the salad tightly with plastic wrap or a lid, and refrigerate for at least 2 hours to allow the flavors to meld together.

If you prefer a firmer texture, drain any excess liquid before serving.