I was in Wales in October, and while for the most part had pretty good food, there was this one egg salad sandwich in Cardiff that was absolutely not my thing. No texture, bland, and way too much mayo, completely disappointing, now having said that I have had many a similar sandwich in delis in the US, and the solution is absolutely not the tuna salad route of celery, after all the gentle nature of eggs can't take that much crunch, so the solution below is alfalfa sprouts.
Even though I didn't want the crunch of celery, the flavor helped brighten it up in the form of celery salt. I also prefer to use mustard powder to avoid the extra vinegar, there already is a little acid in mayo, and I don't want it taking over.
2 hard-boiled eggs
1/4 cup mayo
1/2 tsp mustard powder
1/2 tsp celery salt
1/2 tsp white pepper
dash of fresh black pepper
Handful of alfalfa sports
Lightly toasted bread
A little extra mayo for spreading
Add mayo and seasoning
Mix gently not to break up all the yolk.
Spread a little mayo on slightly toasted bread.
Top with egg salad.
Top with second slice of bread.