In a large cast iron skillet heat 2 tablespoons of the oil over medium heat. Add the onions and the chiles and saute, turning with tongs to make sure they brown evenly, for 6 to 8 minutes, or until golden. Add the salt and pepper, toss to mix, and remove from the heat. Drizzle with the remaining olive oil and serve, drizzled with a little sherry vinegar.
If you can't find small mild chiles, use Anaheims, cut into long, thick strips.
Recipe copyright Mary Sue Milliken and Susan Feniger, 1997, all rights reserved