Preheat grill or barbecue until hot. Or, preheat oven to 240ºC. If grilling or cooking in the oven, place capsicums on cooking foil on a baking tray. If barbecuing, omit baking tray and place on foil directly onto grill. Cook 15 minutes, turning halfway through, or until blackened and blistered. Remove from heat. Place cloth towel soaked in cold water on top. Leave 5 minutes. Peel away skin with a small knife.
Cut flesh into thin strips. Place on a platter. Drizzle with combined oil and vinegar. Refrigerate, covered, 1 hour. Add salt and pepper to taste before serving.