Toast the bread slices in the toaster or in the pan. Rub the toasted bread slices with garlic. Then rub the halved tomatoes until a nice red tomato layer has formed, this is only possible with really ripe tomatoes. Drizzle the bread with a little olive oil and top with Serrano ham.
Pan con tomato can also be made without ham. Then sprinkle the bread with some coarse sea salt.