You can roast red peppers several ways. If you have just one pepper, hold it with tongs over the flame of a gas stove and char on all sides. If you have several peppers, preheat the oven to 450°F, place the peppers on a rimmed baking sheet and roast, turning every 15 minutes, until done (probably half an hour). Place in a bowl, cover with plastic, and let the steam loosen the skin. Once the peppers have cooled, peel off the blackened skin with a paring knife or your fingers and deseed.