I've realized that 90% of the challenge here is properly boiling the egg. You need to boil it so the center sets yet stays moist. You also need to avoid the green/grey ring thing that surrounds the yolk in many hard boiled eggs. I use the same technique here that I learned camping with a hardcore egg enthusiast. It has worked for me flawlessly ever since. The key is to avoid over cooking, and to dunk the eggs in a bowl of icy water to stop the cooking after you remove them from the hot water. I always use good quality eggs - but something to keep in mind, the fresher they are, the harder they are to peel after boiling.
6 large eggs
1-2 tablespoons mayonnaise (or Greek yogurt)
Salt and pepper
A tiny squeeze of lemon juice
2 stalks celery, washed and chopped
1/2 bunch chives, chopped
2 small handfuls of lettuce
8 slices of whole grain bread, toasted
Place the eggs in a pot and cover with cold water by a 1/2-inch or so. Bring to a gentle boil. Now turn off the heat, cover, and let sit for exactly seven minutes. Have a big bowl of ice water ready and when the eggs are done cooking place them in the ice bath for three minutes or so - long enough to stop the cooking. Crack and peel each egg, place in a medium mixing bowl. Add the mayonnaise, a couple generous pinches of salt and pepper, now mash with a fork. Don't overdo it, you want the egg mixture to have some texture. If you need to add a bit more mayo to moisten up the mixture a bit, go for it a bit at a time.
Stir in the celery and chives. Taste, and adjust the seasoning - adding more salt and pepper if needed.
To assemble each egg salad sandwich: place a bit of lettuce on a piece of toast, top with the egg salad mixture, and finish by creating a sandwich with a second piece of toast.
Make 4 sandwiches.