In a 3-4 quart. pot, heat the oil and garlic together. When garlic becomes pale gold and fragrant add the tomatoes, salt, pepper, sugar and basil sprig. Stir well to combine and bring sauce to a boil, then reduce to a simmer. Simmer sauce, 20-30 minutes, stirring occasionally until sauce has thickened and is richly flavored. Remove from heat, check for seasoning and stir in the torn basil leaves.