Place the potatoes in a saucepan and cover with 2 inches water. Generously season the water with salt. Bring to a boil, reduce the heat and simmer until tender, about 10 minutes.
While the potatoes cook, place the bacon in a cold skillet and turn to medium-low heat. Add the olive oil and thyme to the pan. Saute the bacon and thyme until just starting to crisp, about 7 minutes; we want to render the bacon slowly. Once the bacon has rendered some of its fat, add the onions to the bacon and cook until softened, 3 to 4 minutes. Add the vinegar, butter and mustard.
Once the potatoes are cooked, drain them and add immediately to the pan with the sauteed bacon. Stir to coat, adjusting the seasoning, if necessary. Add the remaining fresh herbs, toss and serve.
This salad can be served warm or at room temperature.
Cook's Note: Adding the potatoes while they are still warm will help them to soak up the flavors of the vinaigrette.