How to Make It
Season the chicken breasts with salt and pepper. Tightly roll them up lengthwise and secure with toothpicks at 1-inch intervals.
In a large saucepan, combine the vinegar, 3/4 cup of water and a pinch of salt and bring to a gentle simmer. Add the chicken and cook over low heat until just white throughout, 10 to 12 minutes. Transfer the chicken to a work surface and let cool slightly. Discard the toothpicks. Slice the chicken crosswise into 1-inch-thick rounds.
In a large bowl, whisk the olive oil with the mixed herbs and season with salt and pepper. Add the chicken, turning to coat evenly in the herb oil. Let cool to room temperature, about 30 minutes. Cover and refrigerate for at least 2 hours or overnight. Bring to room temperature and serve with crusty bread.