01 - Place the eggs in a medium saucepan and cover with cold water by about 1 inch. Bring to a rolling boil over medium-high heat, then reduce the heat to low and simmer for 9 to 10 minutes until hard-boiled.
02 - Immediately transfer the boiled eggs to an ice bath or run them under cold running water until completely cool. Peel the shells and roughly chop the eggs into bite-sized pieces.
03 - In a mixing bowl, combine the mayonnaise, Dijon mustard, lemon juice, chopped celery, red onion, and chives. Fold in the chopped eggs and mix gently until evenly coated. Season with salt and freshly ground black pepper to taste.
04 - Carefully separate the lettuce leaves from the head, rinse under cold water if needed, and pat thoroughly dry with a clean kitchen towel or paper towels.
05 - Spoon the egg salad evenly among the prepared lettuce leaves. Garnish with optional toppings such as sliced radishes, extra herbs, or a sprinkle of paprika or chili flakes if desired.
06 - Fold or roll the lettuce leaves around the filling and serve immediately for the best texture and flavor.