- 2 baking potatoes (about 1-1/4 pounds)
- 2 sweet potatoes (about 1-1/4 pounds)
For the dressing:
- 1/3 cup mayonnaise
- 2 tablespoons Dijon-style mustard
- 2 tablespoons extra virgin olive oil
- 2 tablespoons red wine vinegar
- 2 tablespoons capers, drained
- 2 tablespoons chopped pitted green olives (with or without pimientos)
- Freshly ground black pepper
- 2 stalks celery (with leaves if possible), finely chopped
- 2 hard cooked eggs, coarsely chopped (optional)
- 3 scallions, finely chopped
- 1/2 red onion, finely diced (about 1/2 cup)
- 1/4 cup chopped flat leaf parsley, plus a few sprigs, for garnish
- 8 pitted black olives, rinsed and blotted dry
Peel the potatoes and cut into 3/4-inch dice. Place the baking potatoes in a large saucepan with 2 quarts cold, lightly salted water. Bring to a boil and cook for 4 minutes. Add the sweet potatoes and simmer until both types of potatoes are just tender, 4 to 6 minutes, 10 to 12 minutes in all. Drain the potatoes in a colander.
Meanwhile, prepare the dressing. In a large salad bowl combine the mayonnaise and mustard and whisk until smooth. Whisk in the oil, vinegar, capers, green olives, and pepper. Stir in the drained potatoes while still hot and let cool.
Stir in the celery, eggs, scallions, onion, and parsley. Correct the seasoning, adding salt or vinegar: the salad should be highly seasoned. Clean the edges of the bowl with a rubber spatula or a paper towel. Decorate the top of the salad with a black olive and parsley sprigs and serve at once.