1) To cook eggs, add them to the bottom of a large pot and fill with cold water. The water should cover the eggs by a few inches. Place over high heat, covered, and bring to a simmer. Once the water is simmering, kill the heat, but leave it covered, and let sit for 14 minutes.
2) Rinse eggs with cold water immediately and peel. It’s easiest to peel the eggs if you use slightly older eggs and start peeling them at the wider end of the egg.
3) Meanwhile, dice up the celery and red onion finely and stir it together with other ingredients.
4) When eggs are peeled, roughly chop them. You want some big chunks. Fold the eggs into the other ingredients and season well with salt and pepper.
5) To make a sandwich, toast two pieces of bread. Place a crispy piece of lettuce on one piece of bread and pile on some egg salad. Garnish with chives and top with the other piece of toast.
Leftover egg salad will keep for 3-4 days in the fridge.