French Potato Salad with vinaigrette dressing

Ingredients
- 900 gr. (2 lb.) potatoes, unpeeled, e.g. charlotte
- 2 tbsp. red wine vinegar
- Salt/freshly ground black pepper
- ½ tsp. mustard powder
- 6 tbsp. olive oil
- 1 large red onion, cut into thin slices and then into
- 1 cm. (½") pieces
- Flat leaf parsley
- For a vinaigrette dressing the ratio of vinegar to oil is: 1 part vinegar to 3 parts oil
Method
Boil potatoes in their skins until just cooked, about 25 minutes.
Whilst potatoes are cooking, make vinaigrette by putting the red wine vinegar into a bowl and mixing in the salt, pepper and mustard powder before whisking in the olive oil.
Drain the potatoes and peel. Leave a minute or two until you can hold them in a piece of kitchen towel, make an incision the length of the potatoes and gently rub off the peel - or use a knife to help if you like.
Cut the potatoes cross-wise into 5 mm. (¼") slices and put straight into bowl. Stir from time to time whilst doing so, to coat them evenly and to prevent them from sticking.
Peel a large red onion, cut as above and stir in.
Spoon into serving bowl and finally, scatter over 1 tbsp. chopped flat leaf parsley and serve.
Lovely when served warm, but of course may also be eaten cold.
