This is a no-cook protein salad built on canned tuna, hard-boiled eggs, and a sharp Dijon vinaigrette over romaine and arugula. It comes together in about 32 minutes, and between the tuna and eggs it delivers enough protein to work as a real meal, not a side. The mustard dressing is the part worth paying attention to โ it does more work here than most dressings.
The short version of why this works
Two things carry this recipe. First, the dressing uses both Dijon and whole-grain mustard, which means it emulsifies properly โ the mustard acts as the binder that keeps oil and acid from separating into a greasy puddle. Whisk slowly and it turns glossy and thick enough to coat every leaf. Second, the combination of tuna and eggs isnโt just about protein quantity; the egg yolks add a richness that softens the acidity of the lemon juice and vinegar, so the dressing tastes balanced rather than sharp. Get those two things right and everything else falls into place.
What can go wrong
- Watery tuna dilutes the dressing. Drain canned tuna thoroughly โ press it against the colander with a spoon or squeeze it in a paper towel. Even a tablespoon of excess liquid will thin the vinaigrette and make the greens soggy faster.
- Capers that are too salty throw off the seasoning. Rinsing is listed, but a quick 2-minute soak in cold water makes a real difference if your capers are packed in brine rather than salt. Taste one before adding them.
- Red onion thatโs too aggressive. Raw red onion can overpower everything else. If yours is sharp, soak the slices in cold water for 10 minutes, then pat dry. The bite drops noticeably.
- Arugula that wilts before you serve. Baby arugula is more delicate than romaine. If youโre assembling more than a few minutes ahead, keep it separate and fold it in last. Dress it at the table โ a pre-dressed salad goes limp fast.
- Under-seasoned dressing that flattens the whole bowl. The dressing needs to taste slightly too punchy on its own โ it will mellow once it hits the greens and tuna. Taste it before it goes on the salad and adjust salt or lemon accordingly.
Smart swaps
- Capers: If you donโt have them, finely chopped Kalamata olives give a similar briny punch. Use about the same volume.
- Apple cider vinegar: White wine vinegar is a cleaner substitute and keeps the Mediterranean flavor profile intact. Red wine vinegar also works but adds a little more color to the dressing.
- Whole-grain mustard: Marked optional in the recipe, and it genuinely is โ the Dijon does the structural work. The whole-grain version just adds small pops of texture and a slightly nuttier flavor.
- Avocado: If youโre adding it, slice it last and toss it lightly in a little of the dressing to slow browning. It also adds meaningful calories and healthy fat, which helps this hold you longer as a standalone meal.
- Tuna variety: Albacore in olive oil is the richest option. Skipjack in water works fine but is leaner and milder โ compensate with a small extra drizzle of olive oil in the dressing.
Keeping it fresh
If youโre making this ahead, store the components separately: dressed greens are a lost cause after about 30 minutes, but the tuna, eggs, and dressing all keep well. The dressing holds in a sealed jar in the fridge for up to 5 days โ shake or re-whisk before using since it will separate. Hard-boiled eggs keep unpeeled in the fridge for up to a week; peel them the day you plan to eat. For meal prep, pack the romaine and arugula dry in one container, the tuna and chopped vegetables in another, and the dressing in a small jar. Assemble and dress right before eating. Fully assembled and dressed leftovers are edible the next day but the greens will be soft โ if that bothers you, treat it more like a tuna-egg bowl and skip the lettuce on the second serving.
Tuna and Egg Salad with Mustard Dressing
Equipment
- Medium saucepan with lid
- Slotted spoon
- Large mixing bowl
- Small bowl or liquid measuring cup
- Whisk
- Chef's Knife
- Cutting board
- Colander
- Paper towels
Ingredients
For the Eggs:
- 6 large eggs
For the Mustard Dressing:
- 2 tbsp Dijon mustard
- 1 tbsp whole-grain mustard optional, for texture
- 2 tbsp fresh lemon juice
- 1 tbsp apple cider vinegar
- 1 tsp honey
- 1 clove garlic finely grated
- ยฝ tsp kosher salt
- ยผ tsp freshly ground black pepper
- 6 tbsp extra-virgin olive oil
For the Salad:
- 10 oz canned tuna drained; tuna in olive oil preferred
- 4 cup romaine lettuce chopped
- 2 cup baby arugula
- 1 cup cherry tomatoes halved
- ยฝ cup celery finely diced
- โ cup red onion thinly sliced
- 2 tbsp capers drained and rinsed
- 2 tbsp flat-leaf parsley chopped
- 1 small avocado sliced, optional
Instructions
- Cook the Eggs: Place the eggs in a medium saucepan and cover with cold water by about 1 inch. Bring to a gentle boil over mediumโhigh heat, then reduce to a steady simmer and cook for 10 minutes. Transfer eggs to an ice bath with a slotted spoon and cool for 5 minutes to stop the cooking. Peel, then quarter or halve to your preference; set aside on paper towels.
- Whisk the Mustard Dressing: In a small bowl or measuring cup, whisk Dijon mustard, whole-grain mustard, lemon juice, apple cider vinegar, honey, garlic, salt, and pepper until smooth. While whisking constantly, slowly drizzle in the olive oil until the dressing is emulsified and glossy, 60โ90 seconds. Taste and adjust seasoning.
- Build the Salad Base: In a large mixing bowl, combine romaine, arugula, cherry tomatoes, celery, red onion, capers, and parsley. Toss to distribute the aromatics evenly.
- Add Tuna and Dress: Flake the drained tuna into the bowl in bite-size chunks. Drizzle over half of the mustard dressing and gently fold to coat without breaking the tuna, about 30โ45 seconds.
- Finish and Serve: Transfer the salad to a platter or individual plates. Nestle the egg halves or quarters on top, add avocado slices if using, and spoon over the remaining dressing. Finish with a few grinds of black pepper and serve immediately.
Notes
Chefโs Tips:
- Egg Doneness: For jammy eggs, simmer 7โ8 minutes; for firm centers ideal for this salad, 10 minutes is reliable.
- Easy Peeling: Older eggs peel more cleanlyโshock thoroughly in ice water before peeling.
- Tuna Choice: Oil-packed tuna brings richness; if using water-packed, add 1 extra tablespoon olive oil to the dressing.
- Make-Ahead: Dressing keeps 5 days refrigerated; eggs can be cooked and peeled up to 3 days ahead.
- Texture Play: Add crunch with toasted almonds or croutons just before serving (keep any add-ins separate until the last moment).
Nutrition
FAQ
Can I use fresh tuna instead of canned?
Yes, but it changes the dish considerably. Sear a 6-oz tuna steak over high heat for about 90 seconds per side, let it rest, then slice or flake it over the salad. The flavor is less briny and more neutral, so lean into the capers and dressing to compensate.
How much protein does this actually have per serving?
The recipe card lists 479 calories per serving for 4 servings. Between roughly 2.5 oz of tuna and 1.5 eggs per portion, youโre looking at approximately 30โ35g of protein per serving, depending on your tuna brand. Adding the optional avocado doesnโt change the protein much but adds healthy fat that helps the meal sustain you.
Can I make this without eggs if someone has an allergy?
You can, though youโll lose some of the richness that balances the acidic dressing. A handful of white beans or chickpeas makes a reasonable substitute โ they add bulk and a mild creaminess without competing with the tuna.
The dressing broke and looks oily โ can I fix it?
Yes. Pour the broken dressing into a clean bowl, add a fresh teaspoon of Dijon mustard, and whisk vigorously while slowly pouring the broken mixture back in. The fresh mustard re-emulsifies it. This works as long as the dressing hasnโt been sitting for too long.