Dice the onion and celery into small, uniform pieces—this ensures even texture throughout the salad. Measure out the mayonnaise, lemon juice, dill, Dijon mustard, and both quantities of seafood seasoning into separate small bowls. Having everything prepped and measured streamlines the final assembly and prevents scrambling once the shrimp is cooked.

Bring 6 cups of water to a rolling boil in a large pot over medium-high heat. Add 3 tablespoons of Old Bay seasoning and 1 tablespoon of apple cider vinegar to the water—the vinegar adds subtle tang and helps season the shrimp from the inside out. Once boiling, add the shrimp and stir occasionally. Cook for 2-3 minutes until the shrimp turn bright pink and feel firm when pressed; don't overcook or they'll become rubbery. I like to slightly undercook shrimp by a few seconds since they'll continue cooking slightly as they cool.

Drain the shrimp immediately into a colander and rinse thoroughly with ice-cold water to stop the cooking process and cool them down quickly. Once cooled, peel away the shells gently, starting from the head end. Pat the peeled shrimp dry with paper towels to remove excess moisture—this prevents the final salad from becoming watery.

Chop the cooked shrimp from Step 3 into bite-sized pieces, about 3/4 inch—this creates better texture and makes the salad easier to eat. Don't mince them too finely or the salad will feel mushy; you want distinct pieces that maintain some texture.

In a large mixing bowl, whisk together the mayonnaise, lemon juice, Dijon mustard, and the 3/4 teaspoon of seafood seasoning until smooth and well combined. Fold in the diced onion and celery from Step 1, which will soften slightly and absorb the flavors as they sit. Add the chopped shrimp from Step 4 and gently fold everything together until evenly coated, being careful not to break up the shrimp pieces. I prefer to fold rather than stir vigorously—it keeps the shrimp pieces intact and prevents the salad from becoming too dense.

Taste the salad and adjust seasoning with the freshly ground black pepper and additional seafood seasoning if needed. Top with fresh dill and a light sprinkle of extra seasoning. Refrigerate for at least 30 minutes before serving—this allows the flavors to meld and the salad to chill thoroughly, making it more refreshing and easier to serve.