In a bowl, stir together all ingredients. Taste and adjust seasonings as desired. (Tastes best freshly made. You can also refrigerate for up to 3 to 5 days; after refrigerating taste and add a little salt and/or mustard to refresh the flavors.)
If desired, toast the bread. Place the egg salad on the bread and top with lettuce, red onion, and any other toppings desired.