3 cups chopped romaine hearts or Little Gem lettuce

½ medium red bell pepper, seeded and chopped (½ cup)

½ cup chopped English (seedless) cucumber or Persian cucumber

⅓ cup coarsely chopped fresh flat-leaf parsley leaves

¼ to ⅓ cup sliced pitted green olives (optional)

¼ cup chopped red onion

One 7- to 8-ounce jar of tuna packed in olive oil, undrained (may substitute two 4- to 5-ounce cans)

2 tablespoons red wine vinegar

1 teaspoon dried oregano

⅛ teaspoon salt

¼ teaspoon freshly ground black pepper