In a large pot, bring 2 quarts of water to a rapid boil, adding lemon halves, garlic, a bay leaf, and a generous pinch of salt for flavor. Once bubbling, turn off the heat and add the shrimp, ensuring they are fully submerged. Poach for about 3 minutes until opaque and pink. Remove with a slotted spoon and cool in the refrigerator.

Finely dice half of a red bell pepper and one stalk of celery, then slice 3 to 4 green onions thinly. Place in a large mixing bowl.

Once cooled, chop the shrimp into bite-sized pieces and add to the bowl with vegetables. Incorporate mayonnaise, lemon juice, and dill. Adjust salt and pepper to taste. Gently fold until well combined.

Cover the mixing bowl and refrigerate for at least one hour to allow flavors to meld.

After marinating, stir gently and serve in lettuce cups, on buttered rolls, or alongside saltine crackers.