Cook the Shrimp: Fill a large pot with water and add the kosher salt and lemon quarters. Bring the mixture to a boil, then add the shrimp. Cook for 2-3 minutes, or until the shrimp turn pink and are fully cooked. Remove the shrimp from the heat and transfer them to a bowl of ice water to cool. Once chilled, drain and gently pat them dry.

Prepare the Dressing: In a large mixing bowl, combine the mayonnaise, Dijon mustard, white wine vinegar, black pepper, and chopped dill. Whisk until smooth and creamy.

Assemble the Salad: Add the cooked shrimp, minced red onion, and celery to the bowl with the dressing. Gently toss until the shrimp and vegetables are well-coated with the dressing. Adjust seasoning with additional salt, pepper, or lemon juice, if desired.

Chill and Serve: Cover and refrigerate the shrimp salad for at least 30 minutes to allow the flavors to meld. Serve chilled over a bed of crisp lettuce, alongside fresh bread, or layered in a sandwich.