Place the whole peppers on a sheet pan and place in the oven for 30 to 40 minutes, until the skins are completely wrinkled and the peppers are charred, turning them twice during roasting. Remove the pan from the oven and immediately cover it tightly with aluminum foil. Set aside for 30 minutes, or until the peppers are cool enough to handle.
Remove the stem from each pepper and cut them in quarters. Remove the peels and seeds and place the peppers in a bowl along with any juices that have collected. Discard the stems, peels, and seeds. Pour the oil over the peppers. Cover with plastic wrap and refrigerate for up to 2 weeks.