Prepare Hard-Boiled Eggs: Place eggs in a saucepan with cold water. Bring to a boil for about 1 minute, then cover and let sit for 10 minutes. Cool in cold water before peeling.

Cook the Potatoes: Wash and halve or quarter new potatoes. Cover with cold water and add 1 tablespoon salt. Boil for around 12 minutes until fork-tender, then drain and cool slightly.

Blanch Green Beans: In the same pot, bring water back to a boil and add green beans. Cook for 2 to 3 minutes until bright green, then transfer to an ice-water bath to stop cooking.

Make the Vinaigrette: Combine olive oil, lemon juice, white wine vinegar, minced garlic, Dijon mustard, capers, and salt and pepper in a jar. Shake until blended.

Assemble the Salad: In a large bowl, combine parsley, chives, and half of the vinaigrette. Fold in potatoes and green beans, then add sliced hard-boiled eggs and drizzle with remaining vinaigrette.