Place a rack about 4 inches from preheated broiler element. Arrange tomatoes and peppers on a foil-lined baking sheet. Place under broiler and turn occasionally until charred all over. Set aside. Chop tomatoes, including their skins. Remove stems and seeds from all peppers, then place in saucepot. Add remaining ingredients. Bring to a boil and then simmer on low for 45 minutes. Transfer to food processor or food mill and return to saucepot. Add water to adjust consistency.