Blue Giudicarie and white potato salad with Würstel

I used ordinary potatoes and blue Trentino potatoes given by my friend Luigi. This distinctive variety is grown on small plots: blue Giudicarie potatoes.
INGREDIENTS
3 or 4 white potatoes
3 or 4 blue potatoes
6 Würstel, mine German
Half an onion
2 tablespoons mustard
2 tablespoons cider vinegar
1 glass white wine
Salt and pepper
Parsley
I peel and cut potatoes.

I slice 1 cm thick and microwave for speed, or boil normally.

I put in a bowl with water and cover with cling film.

I microwave at full power about 15 minutes.

I drain cooked potatoes.

I peel and slice half an onion.

I soak in cold water 10 minutes, changing a couple of times.

I chop with a knife.

I put in a small bowl with 2 tablespoons cider vinegar.

Then salt and 3 or 4 tablespoons olive oil.

Then 2 tablespoons mustard.

I mix well.

I thin with white wine.

I emulsify and let the dressing develop flavour.

Meanwhile, I grill Würstel.

I slice them.

I add to potatoes.

I add dressing.

I mix with parsley and rest before eating to absorb flavours.