Creamy Shrimp Salad

Name: Creamy Shrimp Salad
Ingredients: 4 cups water; 1 large lemon, halved; 1 tablespoon kosher salt, plus more to taste; 2 teaspoons Old Bay seasoning, divided; 2 pounds small (51- to 60-count) peeled and deveined raw shrimp; 2 celery stalks, chopped, plus 1/2 cup chopped celery leaves, plus more for garnish; 1/3 cup chopped green bell pepper; 1/4 cup finely chopped fresh chives; 10 to 15 fresh tarragon leaves, finely chopped (about 1/2 teaspoon packed); 4 to 5 fresh mint leaves, finely chopped (about 1/4 teaspoon packed); 1/2 cup mayonnaise; 1 1/2 tablespoons Dijon mustard