1. In a small bowl combine shrimp, onions, 2 tablespoons of the olive oil, lemon juice, oregano, and salt and pepper.

2. Slice rolls in half lengthwise. Moisten each half with a little of the remaining olive oil. Arrange tomato slices on the bottom half. Spread shrimp mixture over tomato slices and add top half of roll. Wrap each sandwich tightly in foil. At serving time, slice each sandwich in half or thirds.