Rinse and scrub the potatoes and place in a large saucepan with 1/2 teaspoon sea salt. Cover by one inch with cool water and bring to a boil over high heat. Reduce the heat to medium and simmer until the potatoes are easily pierced with a fork (about 15 to 20 minutes).
While the potatoes are cooking, combine the extra virgin olive oil, Dijon mustard, lemon juice, and diced red onions with a whisk until well blended.
Drain the cooked potatoes in a colander and rinse under cold water until they are cool enough to handle but still warm. Chop the potatoes into 1 inch bites... most of the skin will naturally peel off at this point, but I leave the remainder for a rustic taste and texture.
Toss the potatoes with the olive oil mixture and then add then fold in the chopped tarragon, chives and capers if desired. Add sea salt and pepper to taste.
