Under no circumstances do mustard and pickle relish belong in tuna salad. In between slices of bread, mustard wages war against the pungent fish, and the sour, salty mix is polluted even more by the addition of sweet pickle relish. No flavor other than "yuck" prevails in this mélange of canned fish and hot-dog toppings.
Yet, it seems to be the deli standard. I blame the bozo who first did this for the red-headed-stepchildness of tuna salad as a sandwich filling, compared with the more popular roast beast, ham or pastrami. May this person, whoever they were, not rest in peace—they're responsible for causing Hell on earth, at least during the lunch hour, when the world's people of good taste just want a goddamn tuna-fish sandwich in its proper form.
In these dark tuna-salad times, I've found two places in town that manage not to fuck up my favorite deli sandwich. The first is Grant's Marketplace (2952 Beech St. in South Park), which shows that extra ingredients in the tuna-mayo mix can work wonderfully.
Here, finely diced parsley, celery and dill pickles confetti the salad. Aside from the textural perks of a crunch here and there, the subtle flavors are pleasant in the background. The pickles used are garlicky, with dill, which works far better than sweet relish when it comes to seafood. This mix requires more labor, but Grant's commitment to its extraordinary tuna salad has won the place a customer for life. Hear that, delis? Pick up a knife and chop something with it. Don't puss out by squirting fluorescent-colored stuff into my tuna salad!
Grant's uses Bread & Cie baked goods for its 24 sandwiches, 18 of which you can get half-size. The tuna salad ($6.59 for a whole) is especially good on the rosemary bread—it's got fantastic chew. The craft-soda, -tea and -beer selection is legit, and if you ever see the homemade banana bread on the counter, don't resist. It's not good; it's great.
Next, in an area where you're more likely to see a Ferrari than an affordable menu item, the La Jolla Country Market (1030 Torrey Pines Road) makes a mean "Windansea" wrap ($6.50 whole, $3.99 half). You can get any sandwich in wrap form, which I dig, because the tortillas they use are moist and chewy and hold the contents—even wet tuna salad!—quite well.
The Country Market folks are tuna-salad purists—just Chicken of the Sea, a little more mayo than your average mix and salt. It's made plain so that you can add whatever you want—novel concept, right? They'll even mix in anything by request. Some ask for mustard, one of the sandwich makers told me, adding that he finds its addition gnarly like I do.
Any of the mildly flavored wraps work well with the tuna salad; on my last visit, I chose garlic pesto over my favorite, spinach, and didn't find that much of a difference. Because the salad is creamy and simple, you'll want to add something vinegary, like pickles or pepperoncini.
I'd argue that a wrap is better beach grub than a sandwich; I like to call this version the tuna-salad burrito. It tastes way better than a cold carne asada burrito that'll likely blow out from the heat and steam it endured on your way to La Jolla Shores.