Begin by washing the baby potatoes and cutting them in half. Place the potato halves in a bowl, then drizzle them with olive oil and season with salt and pepper. Transfer the seasoned potatoes to a baking tray.
Preheat the oven to 180°C (350°F), then place the baking tray with the potatoes in the oven. Bake for approximately 30 minutes until the potatoes are golden and tender.
Next, wash the green beans and trim the ends. In a large pot, bring water to a boil and add a generous pinch of salt. Once the water is boiling, add the green beans and cook them for about 7 minutes.
While the green beans are cooking, prepare a bowl of ice water. After 7 minutes, drain the green beans and immediately transfer them to the bowl of ice water to cool. Let them sit in the ice water for 5-10 minutes, then drain again.
In a separate pot, bring water to a boil and cook the eggs for 10 minutes. Once cooked, run them under cold water, peel, and cut them in half.
Wash the lettuce leaves and roughly chop them. Halve the cherry tomatoes and thinly slice the red onions. Drain the tuna.
To prepare the vinaigrette, mix all the vinaigrette ingredients in a small container and shake well to emulsify. Taste and adjust the seasoning if necessary.
Take a large serving plate and layer the ingredients. Start with the lettuce as the base, then add the green beans, cherry tomatoes, red onions, olives, tuna, hard-boiled eggs, capers, and the baked potatoes. Sprinkle some parsley on top and season with salt and pepper.
Just before serving, pour the vinaigrette dressing over the salad.
TIP: If you want to prepare the salad in advance, you can assemble all the ingredients except the dressing. Only pour the vinaigrette dressing over the salad right before serving.
If serving immediately, consider mixing the lettuce, cherry tomatoes, and green beans separately with a small amount of vinaigrette dressing to enhance their flavors before arranging them on the plate.