Copycat recipe
Sub Shop Tuna Salad
Tuna salad made for a sandwich and tuna salad made for a sub are not the same thing. A sub is longer, the filling sits in a trough of bread, and anything loose runs to the ends within a couple of minutes.
So this version is drier and coarser than a standard tuna salad, with the seasoning pushed up to compensate for the fact that it will be eaten alongside bread, lettuce and tomato rather than on its own.

Ingredients
Base
- 3 tins (about 400g drained) tuna in springwater, not oil
- 90g mayonnaise — full fat, and less than you think
- 1 tbsp red wine vinegar
- 1 tsp Dijon mustard
Texture and seasoning
- 2 celery sticks, finely diced
- 3 tbsp finely diced white onion
- 1 tsp dried oregano
- ½ tsp fine salt
- ½ tsp coarse black pepper
- Optional: 2 tbsp chopped hot cherry peppers
Method
Drain properly, then drain again
Tip the tuna into a sieve and press it firmly with the back of a spoon for a full minute. Most of the water you are about to remove would otherwise end up in the bread. Springwater tuna rather than oil, because you want to control the fat yourself.
Flake coarsely, do not mash
Break the tuna up with a fork into visible flakes and stop early. Mashed tuna salad becomes a paste, and a paste has nothing to grip the roll with — it slides out of the far end of the sub as you eat.
Dress lightly
Fold in the mayonnaise, vinegar and mustard. It should look slightly under-dressed. Celery and onion will release a little moisture over the next half hour and bring it to where you want it.
Add the crunch last
Fold through the celery, onion, oregano, salt and pepper with as few strokes as you can manage. Every extra fold breaks down more tuna and moves you back towards paste.
Rest 30 minutes cold
The oregano needs time to hydrate and the onion needs time to lose its raw edge. Straight from the bowl it tastes sharp and disconnected; after half an hour it reads as one thing.
Notes & troubleshooting
- Weigh the mayonnaise the first time. Almost everyone over-dresses tuna by roughly half.
- Dice the celery smaller than feels right — 3mm. Large pieces make the filling unstable in a long roll.
- For a lighter version, replace a third of the mayonnaise with plain Greek yoghurt. Any more and the vinegar starts to taste sour.
- Keeps two days refrigerated. Beyond that the celery softens and the whole thing goes watery.
- Building the sub: tuna directly on the oiled bread, lettuce and tomato above it, never the other way round.
Questions
Tuna in oil instead of springwater?
It works but reduce the mayonnaise to about 60g, or the result is heavy. Springwater is easier to control, which is why it is the default here.
Why vinegar in tuna salad?
Mayonnaise is fat and tuna is rich. Without an acid the filling tastes flat by the third bite. A tablespoon of red wine vinegar is not detectable as vinegar and keeps the whole thing lively.
Can I make it the day before?
Yes, and it is arguably better. Add the celery on the day if you can, since it is the first thing to lose its crunch.
Is this how a sub shop makes it?
No shop publishes its recipe. This is an independent version built for the way a sub is constructed, rather than a transcription of anyone else.
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