Place potatoes in a medium pot and cover with cold water by 1 inch. Add 1/2 tsp salt. Bring to a boil over high heat, then reduce to a simmer and cook until just tender when pierced with a knife, about 12–15 minutes depending on size. Drain and let cool slightly, then slice into halves or thick rounds.

Cook eggs

While potatoes cook, bring a small pot of water to a gentle boil. Add eggs and cook for 9 minutes for firm but creamy yolks. Transfer eggs to an ice bath for 5 minutes, then peel and quarter.

Blanch green beans

Bring a separate pot of salted water to a boil. Add green beans and blanch for 2–3 minutes until bright green and tender-crisp. Immediately transfer to an ice bath to stop cooking. Drain and pat dry.

Prepare tuna

If using canned tuna: drain well and flake into large pieces. If using fresh tuna: season lightly with salt and sear in a hot skillet with 1 tsp oil, 1–2 minutes per side for medium-rare, then let cool and slice thinly.

Assemble salad

On a large platter or in a bowl, arrange mixed greens as a base. Scatter halved potatoes, blanched green beans, tomato wedges, olives, cornichons (if using), and flaked/sliced tuna over the greens. Tuck quartered eggs around the platter. Sprinkle capers and chopped parsley over the top.

Dressing (Classic Dijon-Shallot Vinaigrette)

In a small bowl or jar combine minced shallot, minced garlic, Dijon mustard, red wine vinegar, and lemon juice. Whisk or shake to combine. Slowly stream in 6 tbs olive oil while whisking constantly (or add to jar and shake vigorously) until the dressing emulsifies. Season with 1 tsp salt and 1 tsp freshly ground black pepper. Taste and adjust acidity or seasoning as needed.

Finishing & serving

Drizzle the dressing evenly over the assembled salad (or serve on the side). Finish with the 1 tbs extra-virgin olive oil, additional cracked black pepper, and a sprinkle of chopped parsley. Serve immediately so greens remain crisp. Leftovers keep well refrigerated for 1 day; store dressing separately.