Cut your stale bread into cubes. You should have about 7 cups. Set aside.
Heat the oil in a large, heavy soup pot over medium-low heat. Add the onion and cook, stirring, until tender, about 5 minutes. Add the garlic and cook, stirring, for about a minute, until fragrant.
Add the tomatoes, tomato paste, sugar, red pepper flakes, and one teaspoon salt and about 1/2 teaspoon of pepper, and cook, stirring occasionally, until the tomatoes have cooked down, about 10 minutes.
Stir the bread cubes into the tomatoes. Add the water or broth, and half the basil. Bring to a simmer and simmer, stirring and mashing the bread, for about 10 minutes, until the soup is thick, like oatmeal.
Stir in the remaining basil, taste and adjust seasoning. Serve hot, warm, or room temperature.