1/4 cup olive oil
24 pearl onions, peeled and stem end trimmed but left intact, and halved lengthwise
12 small, whole pepperoncini, or other small, mild chiles (see Note)
1 teaspoons salt
1 tablespoon freshly ground black pepper
Sherry vinegar, for drizzling
If you can't find small mild chiles, use Anaheims, cut into long, thick strips.