Niçoise salad is a classic French salad originating from the city of Nice in the French Riviera. Filled with both fresh and cooked ingredients like tuna, hard-boiled eggs, tomatoes, green beans, lettuce, and boiled potatoes in a tangy lemon dressing, it's the perfect summertime salad.
In a small bowl, whisk together all of the ingredients for the lemon dressing until combined. Set aside.
Bring a large pot of salted water to a boil. Gently place the eggs in the water and cook for 7-10 minutes. Seven minutes will give jammier insides, whereas 9-10 minutes will result in more hard-boiled eggs. Carefully remove the eggs and transfer them to an ice bath for a few minutes, then gently crack, peel, and halve each one.
Bring a second pot of salted water to a boil. Add the baby potatoes and cook for 12-15 minutes or until fork tender. Using a slotted spoon, remove the potatoes from the pot (leaving the water in the pot). Transfer the potatoes to an ice bath, then cut them into quarters.
Return the water to a boil. Add the trimmed green beans. Blanch for 1-2 minutes or until they turn a bright green color. Transfer to an ice bath to chill before draining.
Over a large platter or salad plate, arrange the mixed greens. The greens will serve as the base for the salad.
Next, arrange the green beans, potatoes, eggs, olives, tomatoes, tuna, and red onion. Drizzle the dressing over the salad and gently toss (if desired).
Notes
Leftovers: For best results, store the salad ingredients separately in airtight containers in the refrigerator for up to two days. The salad dressing can be stored in an airtight container in the fridge for up to 2 weeks. Shake well before using.