1. Steam or boil the potatoes with their skins on.
2. Peel them and cut into approximately 1cm thick slices, then place them in a salad bowl.
3. Peel and finely chop the onions. Sauté the onions and bacon in a pan (with a little olive oil if your pan is not non-stick) for about 15 minutes, stirring regularly, until the onions are golden brown.
4. Add the onions and bacon to the potatoes.
5. Season with salt and pepper to taste.
6. Make a vinaigrette dressing using mustard, oil, and balsamic vinegar.
7. Pour this dressing over the salad.
8. Finally, add the fresh cream just before serving.