Heat oven to 400 degrees F. Split pitas in half. Cut into bite-size pieces. Place on ungreased baking sheet.
Bake in 400 degree F oven until golden, about 5 minutes; set aside.
Combine tomatoes, watercress, cucumber, mint, green pepper and green onion in large bowl.
Combine oil, lemon juice, salt, black pepper and coriander in small bowl. Add to tomato mixture. Add toasted pita pieces just before serving. Makes 6 servings.