Begin by preparing the components. Boil the quail eggs for 4 minutes, then immediately transfer them to an ice bath to stop the cooking process. Once cooled, gently peel the eggs and set aside.

Boil the potatoes in salted water until tender, around 10 to 12 minutes. Drain and set aside to cool slightly.

Blanch the green beans in boiling salted water for 3 minutes until bright green and slightly tender-crisp. Immediately transfer them to an ice bath to cool, then drain and set aside.

Prepare the vinaigrette: Finely mince the shallot and whisk it in a small bowl with the Dijon mustard, lemon juice, olive oil, and salt. Whisk until well emulsified.

Heat a drizzle of olive oil in a skillet over medium-high heat. Season the tuna steak with salt and freshly ground black pepper. Sear the tuna for 1 to 2 minutes per side for rare to medium-rare, depending on your preference. Let the tuna rest before slicing.

To assemble: Gently slice the cooked potatoes and arrange them on a plate. Next, place the blanched green beans and halved cherry tomatoes around the potatoes, then top with the black olives.

Slice the seared tuna and arrange it over the vegetables. Halve or quarter the quail eggs and add them to the plate.

Drizzle the vinaigrette over the salad. Finally, sprinkle with fresh parsley and serve immediately.