Go fish.
Tuna is one of my favorite sandwiches. Clearly, the people at Pajiba share my feelings, as a recent article extolled them as the best of the basic sandwiches.
However, as often as not, I've only had them with mild accoutrements, like lettuce and the occasional piece of cheese. Reading through some of the comments, I've been eating these all wrong. Check out some of these variations:
@zoozoopedals - Tuna with sweet relish, a chopped egg, red onion, minced celery and a shit ton of mayo.
@megbon - I do half mayo and then mustard, some hard boiled egg and pickled relish.
@Sara_Tonin00 - I love tuna with lemon juice, capers, red onion or shallot and a lot of fresh parsley (fresh dill is also good). And good olive oil. And fresh cracked black pepper.
Sounds like I've got some homework (and shopping) to do.