Lay the peppers, cut side down, on a baking sheet and place under the broiler until skin turns black. Remove from the oven and cover with a kitchen towel; allow to cool.
Cut a small X in the base of the tomatoes. Place in a small bowl, cover with boiling water, and set aside for 2 minutes. Drain and cool. Peel skin from peppers and tomatoes; chop flesh finely.
In a medium saucepan combine onion, apple, vinegar and sugar with tomatoes and peppers. Heat over medium heat, stirring until sugar has dissolved; bring to a boil. Reduce heat to low and simmer for 30 minutes. Store, covered, in the refrigerator for up to 1 month.
