Rub garlic on slices of bread, brush with a little oil, and bake in the oven until golden and dry. Chop tomatoes in a food processor, and finely chop the celery. Bring to the boil with 2 teacups water, and add salt, oil, oregano and pepper. Continue to simmer till the soup thickens a little. Serve in a tureen, topped with the bread cut into croûtons, and sprinkle with finely chopped basil.