Ahi Tuna Niçoise Salad and Mustard-Tarragon Dressing

Bright, fresh, and packed with flavor, ahi tuna Niçoise salad is a vibrant twist on a classic French dish. The tender seared tuna pairs beautifully with crisp greens, olives, and eggs, all brought together by a tangy mustard-tarragon dressing that adds a delightful herbal kick. Whether you’re looking for a light lunch or a satisfying

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Ahi Tuna Niçoise Salad Tossed in Mustard-Tarragon Dressing

Why This is Delish

This salad has everything going for it. The seared ahi tuna is silky and rich, the vegetables are fresh and bright, and that mustard-tarragon dressing is something you’ll want to put on everything. The combination of textures — creamy potatoes, crisp green beans, juicy tomatoes, and that perfectly seared tuna — makes every bite interesting. Plus, most of the components can be prepped ahead of time, making assembly a breeze.

How to Make Ahi Tuna Niçoise Salad

Start by making the marinade for the tuna. Mix together the soy sauce and sesame oil, then stir in the white and black sesame seeds. Coat the ahi tuna with avocado oil, then let it marinate in the soy-sesame mixture for at least 15 minutes.

While the tuna marinates, bring a large pot of salted water to a boil and cook the mini potatoes until fork-tender, about 10–12 minutes. Drain and let them cool slightly, then season with salt and pepper.

In the same boiling water (or a fresh pot), blanch the green beans for 2–3 minutes, then drain and rinse under cold water to stop the cooking. Toss them with fresh lemon juice, a grated garlic clove, salt, and pepper.

Make the mustard-tarragon dressing by whisking together the olive oil, honey, chopped fresh tarragon, Dijon mustard, a splash of red wine vinegar, grated garlic, and lemon juice. Season with salt and pepper to taste.

When you’re ready to serve, heat a pan over high heat until very hot. Sear the marinated ahi tuna for about 60–90 seconds per side — you want a nice crust on the outside while keeping the center beautifully rare. Let it rest for a minute, then slice.

To assemble, arrange the baby gem lettuce on a large platter or individual plates. Add the cherry tomatoes, Castelvetrano olives, cooked potatoes, and dressed green beans. Lay the sliced ahi tuna over the top and drizzle everything generously with the mustard-tarragon dressing. Finish with a squeeze of lemon, salt, and pepper.

Variations That Spice Ahi Tuna Niçoise Salad Up

Swap the ahi tuna for seared salmon or even a good quality canned tuna if you want something more low-key.
Add soft-boiled eggs for a more traditional Niçoise experience
Throw in some sliced radishes or cucumber for extra crunch and freshness.

Substitutions For Your Dietary Needs

Use coconut aminos instead of soy sauce to make the marinade gluten-free and lower in sodium.
Swap honey for maple syrup in the dressing to keep it vegan (and skip the tuna for a fully plant-based version with chickpeas or roasted tofu).
No Castelvetrano olives? Kalamata olives work great and add a slightly briner, bolder flavor.

Recipe Hacks & Tips

Make sure your pan is screaming hot before you sear the tuna — that’s the key to a good crust without overcooking the inside
Don’t over-marinate the tuna; 15–30 minutes is plenty. Too long and the soy sauce will start to break down the fish
Prep the potatoes, green beans, and dressing ahead of time so all you have to do at mealtime is sear the tuna and assemble
Slice the tuna against the grain for the most tender, clean cuts

Serve These Delicious Dishes

How to Store Leftovers

The components of this salad store best separately. Keep the cooked potatoes, green beans, and dressing in individual airtight containers in the fridge for up to 3 days. Leftover seared tuna can be stored in the fridge for up to 2 days — it’s delicious cold over the salad the next day. Avoid dressing the greens ahead of time, as they’ll wilt quickly once dressed.

Common Questions

Can I serve the tuna fully cooked instead of rare?

Absolutely. If you prefer your tuna cooked through, just sear it for a bit longer on each side, about 2–3 minutes per side depending on thickness. It will have a firmer texture but will still taste great with the dressing and vegetables.

What is the best cut of tuna to use?

Look for sushi-grade ahi tuna (yellowfin or bigeye) from a reputable fishmonger or grocery store. Sushi-grade means it’s been handled and frozen in a way that makes it safe to eat at a rare or medium-rare temperature, which is what you want for this dish.

Can I make the dressing ahead of time?

Yes! The mustard-tarragon dressing keeps well in the fridge for up to 5 days. Give it a good whisk or shake before using, as it may separate as it sits.

Can I use dried tarragon instead of fresh?

Fresh tarragon is highly recommended here — it has a distinctive anise-like flavor that really makes the dressing sing. If you can only find dried, use about 1 teaspoon in place of the 2 tablespoons fresh, but know the flavor will be more muted.

Ahi Tuna Niçoise Salad and Mustard-Tarragon Dressing

This ahi tuna Niçoise salad is a fresh, vibrant twist on the French classic — seared sesame tuna, crisp veggies, and a tangy mustard-tarragon dressing that ties it all together. Perfect for lunch or dinner!

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Yields: people

Ingredients

Ahi Tuna

8 Ounces Sushi Grade Tuna
⅓ Cup Soy Sauce
¼ Cup Sesame Oil
2 Tablespoons White Sesame Seeds
2 Tablespoons Black Sesame Seeds
1 Tablespoon Avocado Oil

Salad

2 Cups Baby Gem Lettuce
1 Cup Cherry Tomatoes halved
½ Cup Castelvetrano Olives
½ Lemon juiced
Salt & Pepper to taste

Green Beans

1 Cup Green Beans
½ Lemon juiced
1 Clove Garlic grated
Salt & Pepper to taste

Potatoes

⅓ Package Mini Potatoes
Salt & Pepper to taste

Mustard-Tarragon Dressing

½ Cup Olive Oil
2 Tablespoons Honey
2 Tablespoons Fresh Tarragon chopped
1 Tablespoon Dijon Mustard
1 Splash Red Wine Vinegar
1 Clove Garlic grated
½ Lemon juiced
Salt & Pepper to taste

Instructions

Prepare the Ahi Tuna Marinade and Tuna

Mix ⅓ cup soy sauce and ¼ cup sesame oil in a bowl.
Add 2 tbsp white sesame seeds and 2 tbsp black sesame seeds.
Coat the ahi tuna with 1 tbsp avocado oil.
Marinate the tuna in the soy and sesame mixture for at least 15 minutes.

Cook the Potatoes

Bring salted water to a boil.
Add mini potatoes and cook until fork-tender, about 10-12 minutes.
Drain and let cool slightly.
Season with salt and pepper to taste.

Prepare the Green Beans

Trim and blanch 1 cup of green beans in boiling salted water for 2-3 minutes.
Drain and rinse under cold water to stop cooking.
Toss the green beans with juice of ½ lemon, 1 grated garlic clove, salt, and pepper.

Make the Dressing

In a bowl, whisk together ½ cup olive oil, 2 tbsp honey, 2 tbsp chopped fresh tarragon, 1 tbsp Dijon mustard, a splash of red wine vinegar, 1 grated garlic clove, and juice of ½ lemon.
Season with salt and pepper to taste.

Assemble the Salad

Slice the marinated ahi tuna and sear it quickly in a hot pan until cooked to your liking.
On a large platter or individual plates, arrange 2 cups baby gem lettuce, 1 cup halved cherry tomatoes, and ½ cup Castelvetrano olives.
Add the cooked potatoes and dressed green beans.
Place the sliced ahi tuna on top.
Drizzle the salad with the mustard-tarragon dressing.
Season with additional salt and pepper if needed.