1. Preheat the oven to 400°F. Lay the slices of bacon on a parchment-lined baking tray and bake for about 10 minutes, or until crisp. Drain on paper towels.
2. While bacon cooks, wash the leeks thoroughly, trim the ends and slice into thin rings. Heat the oil in a large saucepan and sauté half the sliced leeks 3 minutes. Add 2 cups beans, pasta sauce and vegetable broth and bring to a boil.
3. Simmer 5 minutes. Remove from heat and purée with a hand blender. Return to heat and add the remaining leeks, beans and oregano. Simmer 3 minutes.
4. Ladle soup into 4 bowls and top each serving with 2 slices of bacon.
Per serving: 587 calories, 34g fat, 11g saturated fat, 50mg cholesterol, 1107mg sodium, 47g carbohydrate, 10g fiber, 4g sugar, 24g protein