Heat the broiler. Place the peppers, skin side up, on a foil-lined baking sheet; broil 4 inches from the heat until charred, 18 to 20 minutes. Transfer to a large bowl. Cover with plastic wrap; steam for 2 to 3 minutes. Using a paper towel, rub off the pepper skins, reserving any juices in the bowl. Thinly slice the peppers crosswise into 1/4-inch strips; return to the bowl. Set aside.