a pinch of white pepper. and homemade mayo, since we have all those fresh eggs anyways.
Honestly, I'm not a fan, particularly of the mustard-heavy varieties. Mustard is normally added as an emulsifier. If there's enough to serve that purpose, there's enough in the recipe. My view anyways.
More likely to add chopped boiled eggs to other things, like ham salad or tuna salad. I don't much care for tuna salad either, but the addition of chopped boiled egg makes it better (again, my view) than either egg salad or tuna salad alone. White potato salad, also - though that gets a bit more mustard. and eggs help control the saltiness of ham salad, assuming you don't also brine and smoke your own hams.
Now I'm hungry.