Halve the rolls lengthways. Lightly sprinkle the cut surfaces with water. Bake at 200°C (400°F) for 10 minutes until the cut sides are golden and crispy.
Rub the crispy cut surface of each roll with the cut side of a garlic clove half, then rub with the cut side of a tomato half. Drizzle with olive oil. Top each with 2 slices of Serrano ham. Serve lukewarm.