How to Make It
Bring a large pot of water to boil. Season water generously with salt. Cut lemon in half and reserve 1 tsp. lemon juice. Place remaining lemon halves in the water. Boil for 3 minutes. Remove from heat, add shrimp and cover pot. Allow shrimp to sit in the covered pot for 3 to 4 minutes, until the shrimp have turned pink and curled. Drain shrimp and immerse in ice water for 1 minute to stop the cooking process. Remove from ice water and cut shrimp into 1-inch pieces.
In a large mixing bowl, combine reserved lemon juice with mayonnaise, onion, celery, potato, vinegar, Dijon, salt, pepper, garlic, and chopped dill. Gently stir ingredients together to combine. Add shrimp pieces and fold into mixture. Garnish with additional dill.