4 potatoes, peeled or scrubbed, cut into 1/4-inch cubes
1 tablespoon Dijon mustard
8 large green olives, sliced
2 pickled jalapeños, stemmed, seeded and coarsely chopped
12 radishes, trimmed and sliced thin
4 scallions, trimmed and minced
3/4 cup chopped cilantro leaves
2 tablespoons cider vinegar
2 tablespoons olive oil
1/2 teaspoon salt
1/2 teaspoon freshly-ground black pepper

Put the potatoes in a pot; add water to cover and bring to a boil. Reduce heat to simmer until the potatoes are soft all the way through but not disintegrating, about 8 minutes. Drain and set aside to cool and dry out a bit, 15 to 20 minutes.

Transfer the potatoes to a large bowl, add the mustard, and toss to coat. Add remaining ingredients and gently mix.

Serve right away at room temperature or serve chilled.