Mash dash of salt and garlic with a mortar and pestle or the back of a spoon to make a fine paste. Combine garlic mixture and oil in a small bowl.
Place bread on grill rack; grill 1 minute on each side or until golden brown.
Rub both sides of toasted bread slices with cut sides of tomatoes, squeezing slightly to leave pulp, seeds, and juice on bread. Discard tomato peels. Spread garlic mixture over bread slices; sprinkle with 1/4 teaspoon salt and pepper. Cut each slice diagonally in half. Arrange ham and cheese over bread pieces, and sprinkle with olives. Serve immediately.