1. Place potatoes in a medium-size saucepan and add enough cold water to cover by 1 inch. Lightly salt and bring to a boil. Reduce to a moderate simmer and cook for 15 to 20 minutes or until fork tender. Drain.
2. Cut potatoes into halves or quarters, depending on the size, so each piece is about 3/4 -inch. Place in a large bowl with green pepper, onion, alcaparrado and cilantro.
3. In a bowl, whisk oil, vinegar, brine, salt and pepper. Gently toss with potato mixture and let stand, covered, at room temperature until cool.
4. Serve at room temperature or chilled.Note:
5. If you cannot find alcaparrado (a mix of Manzanilla olives, pimiento and capers) at your local supermarket, assemble your own substitute: stir together 1/2 cup chopped pimiento-stuffed olives and a tablespoon of capers.