Place the Cornish new potatoes in a saucepan and cover with cold salted water. Bring to a gentle boil, then simmer for 12–15 minutes or until tender when pierced with a knife. Drain and let cool slightly, then while warm halved or quarter depending on size. Set aside to cool to room temperature.

Cook eggs

Place eggs in a small saucepan and cover with cold water. Bring to a boil, then cover, remove from heat and let sit for 8 minutes for firm (slightly creamy) yolks. Transfer eggs to an ice bath for 5 minutes, peel and cut into halves or quarters. Reserve.

Prepare beans and lettuce

If using fresh bobby beans or fine green beans: bring a separate pot of salted water to a boil, add beans and cook 2–3 minutes until tender-crisp. Drain and immediately plunge into ice water to stop cooking and preserve color; drain and pat dry. Trim and separate little gem lettuce leaves, rinse and spin dry. Arrange lettuce on the serving platter or individual plates.

Dressing

Whisk together red wine vinegar, lemon juice, Dijon mustard and minced garlic in a small bowl. Slowly stream in the extra virgin olive oil while whisking to emulsify. Stir in sea salt and black pepper to taste. Taste and adjust acidity or seasoning. Reserve 2 tablespoons of dressing for tossing warm potatoes so they absorb flavor; keep the rest for finishing the salad.

Tuna & Garnish

Season and sear tuna

Pat the yellowfin tuna dry and season lightly with salt and pepper. Heat a heavy skillet or cast-iron pan over high heat until very hot. Add 2 tbsp olive oil. Sear the tuna for 30–45 seconds per side for rare (adjust 60–90 seconds per side for medium), turning with tongs to get an even crust; do not overcook. In the last 15 seconds, add the butter (optional) and spoon the foaming butter-oil over the tuna. Remove and rest for 2 minutes, then slice into 1 cm thick medallions.

Prepare anchovies and olives

Drain anchovies and pat dry. Halve or leave whole as preferred. Pit the Kalamata olives if not already pitted. Roughly chop or leave whole according to preference. Chop parsley and have capers and cherry tomato halves ready.

If you prefer a warm-nicoise: toss the warm cooked potatoes in the reserved 2 tablespoons of dressing so they pick up flavor.

Assembly & Finish

On the platter with little gem leaves, arrange the tossed warm potatoes, bobby beans, cherry tomato halves, Kalamata olives, anchovy fillets and capers in sections (classical niçoise style) or mixed if you prefer. Nestle the sliced seared yellowfin tuna over the salad. Place the halved eggs around the platter.

Drizzle the remaining dressing over the assembled salad, or serve on the side. Sprinkle chopped parsley and grind a little extra black pepper over the top. Taste and add more flaky sea salt if needed.

Serve immediately while the tuna is still slightly warm, with crusty bread on the side if desired.