1. In a deep pot, heat 4 tablespoons of extra virgin olive oil. Fry the garlic, onions, pancetta, and fennel seeds. Add all the vegetables and cook for 5 minutes, stirring. Cover and set aside.
2. In a large quantity of salted water, cook the pre-soaked borlotti beans with the sage for about 2 hours. Drain and reserve the water.
3. In a blender, puree half of the beans. Add the puree, reserved water, and remaining beans to the vegetables and cook for 30 minutes.
4. Add the corn flour and mix well to achieve a creamy texture, dense enough to hold a spoon.
5. Drizzle each portion with a jet of extra virgin olive oil; add pepper to taste and serve immediately.