Heat the oil in a heavy 4-quart pot over medium heat. Add the garlic, onion, string beans, tomato, salt, and pepper. Stir well to coat with the oil. Cover and cook, stirring occasionally, for 10 minutes, or until the vegetables have softened and released some of their juices.
Add the tomato paste, water, cloves, and the cayenne, stirring well to mix thoroughly. Coarsely chop the basil, then stir it into the string bean mixture.
Cover and bring to a medium-high boil. Cook, stirring occasionally, for 15 to 20 minutes, or until the string beans are tender. Taste for seasonings.