Preheat oven to 350°.
Combine first 6 ingredients in a small bowl, stirring with a whisk.
Combine pepperoni and next 6 ingredients in a medium bowl. Pour vinegar mixture over pepperoni mixture, and toss gently. Cover and chill at least 1 hour.
Place pitas on a baking sheet, and bake at 350° for 3 to 4 minutes or just until warmed.
Place 1 lettuce leaf in each pita half, and spoon 1/2 cup pepperoni salad into each half.