I've been working on something like a theory of tuna salad, a set of general principles that accounts for all of the various ingredients and techniques one might need and also those that should be avoided. I'm not positive that I have tried every possible permutation of this classic, but the state of my knowledge is now sufficiently advanced to share some of my findings with you.
I offer this up not because I don't think that you already know how to make tuna salad but for two reasons. First, gourmet sandwich places and cookbooks seem to have decided that it's a virtue to make tuna salad without mayonnaise. Thus one menu (probably many, actually) offers "olive oil tuna salad," basically advertising that it's not made with mayo. This is wrongheaded, trendy nonsense. Mayonnaise is delicious. Second, the most basic preparations, like Martini cocktails and grilled steaks, are often deceptively hard to perfect. I think this is true of tuna salad, which is easy to make but not as easy to make well.
So without further ado:
1. The fish. White (albacore) tuna packed in water is always preferable for tuna salad. Light tuna, which is a whole different species (skipjack, tongol or yellowfin) is cheaper and stronger tasting. The exception is the kind packed in olive oil, which is more expensive (sometimes much more) but this stuff doesn't mix well with commercial mayo and since it's more of an investment, it's a waste to use it in tuna salad. Put this good stuff in salads dressed in vinaigrette or in pasta sauces. Albacore tuna is said to be dry in comparison with other kinds, but since you are going to mix many moist ingredients with it, dryness doesn't matter.
1. a. Solid or chunk? Solid. A can of solid white tuna contains a product that actually looks like a cooked piece of fish. The visuals inside a can of chunk tuna are not pleasing. Exception: the tuna packed in pouches instead of cans can't be solid because it gets smushed in packaging. Even smushed, it still looks more like solid than chunk. Pouch tuna is an excellent product. It requires no draining and takes up less space in the pantry.
2. Crunchy bits. Celery, destringified with a veggie peeler and finely minced, at a ratio of half a rib per sandwich. This works out to one rib for a regular-size can (yield two sandwiches) or one and a half ribs for one large pouch (yield three sandwiches). By finely minced I mean that the pieces of celery should be minuscule.
2. a. Sour bits, which may also be crunchy. Here you have two options: prepared sweet pickle relish (the iridescent green relish, easily obtained in Chicago and environs and always a condiment on Chicago hot dogs, is very good), about one teaspoon per sandwich; or minced cuke pickles. If using minced pickles, you can't do better than French cornichons, two-to-three per sandwich. Trader Joe's sells these at a nice low price but they're not quite as good as Maille. American gherkins or "midgets" are ok. Big fat dill pickles are your last choice because they contain too much water and affect the tuna salad texture adversely.
2. b. Hard cooked egg: no. My opinion is that hard cooked egg is a filler ingredient used to stretch the quantity of the tuna salad. It doesn't contribute a desirable flavor or texture. If eggs are what you want, make egg salad.
3. Dressing. Three options: Hellman's mayonnaise (apparently called Best Foods in the western U.S.); another brand of mayonnaise; homemade mayonnaise. I don't love using homemade mayonnaise in tuna salad because it lacks sweeteners and preservatives and, seriously, it doesn't taste the same. It's good, it has its place, but it's not the same.
I don't support lowfat mayo. If you're looking for something very low in fat, don't make tuna salad.
I cannot tell you how much mayonnaise to put in your tuna salad any more than I can tell you how often to gaze into the eyes of your beloved. Only you know how much.
(Yes, there is a condiment that starts with "M" that you'll find near the Hellman's in the supermarket. Let's not mention its name.)
3. a. Additions to the dressing: I like to drizzle perhaps half a teaspoon of pickle juice (any kind) into the mix and I always add a pinch of salt and a few grinds of black pepper. Alternatives here would include lemon juice (subbing for the pickle juice), other hot spices (cayenne pepper, wasabi powder), mustard, or prepared or fresh horseradish. If you have leftover tartar sauce (homemade I hope) you could use some of it. Herbs? I don't know. The pickles and their juice are flavored with tarragon or dill but I wouldn't go adding those things fresh to the tuna salad. Chopped capers are acceptable but not my thing. My preference is simplicity: mayo, pickle juice, salt, and pepper. I still haven't tried shallots or anchovies. Maybe they're good too but I doubt it.
4. Mixing. It doesn't matter what order you add ingredients but one thing is crucial. You must press with the tines of a fork against the flakes of fish to break them apart and amalgamate them into the other ingredients. I do this for a good minute or two. Press, mix, press, mix, press, mix. Flex your muscles. It should be well blended.
5. Bread. Obviously, freshness is vital. We almost always have our tuna on some kind of whole wheat but the bread above is sourdough from the Milwaukee Public Market, which sells good breads. Their challahs are even surprisingly acceptable.
5. a. Additions to the sandwich. Not necessary. Properly made tuna salad served on fresh bread needs no additional spread, vegetable, or condiment, but a leaf of crisp lettuce is nice.
5. b. Variation: the tuna melt. Best open-faced on an English muffin. Toast a split muffin halfway, just until the surfaces are no longer soft but before they take any color. Top with tuna salad, and then top that with grated sharp cheddar (or Gruyere, or whatever). Heat until the cheese has melted.
(In case you were wondering, the chips in the picture are Kettle brand sea salt and vinegar and I think they taste like detergent.)