1. In a small bowl, combine the onions, water, vinegar, salt, and pepper. Let sit at room temperature for 5 minutes to allow the flavors to develop. Add 1/2 cup of the oil to the vinegar mixture. Add additional to taste. 2. In a large bowl, combine the lettuce, roasted peppers, olives, haricots verts, cucumber, and herbs. Toss with enough dressing to coat, and season to taste with additional salt and pepper. Serve any remaining dressing on the side.