Place the beans in a saucepan, with cold water to cover. Bring to a boil, remove from the heat. Let stand 1 hour, then drain.
In a Dutch oven over medium heat, add 3 tablespoons of the olive oil. Add prosciutto, cook, turning occasionally to allow to all sides to caramelize, about 5 minutes. Add halved onion, carrot, celery and sage to the pot, and add with beans. Add the water and stir well. Simmer gently, uncovered, until beans are tender, about 1 1/2 hours. Season with salt. Remove from the heat, and let cool in the liquid.
In another large pot, heat remaining 3 tablespoons of the oil over medium heat, then add the fennel, chopped onion, garlic, and a pinch of salt. Cook until vegetables are softened but not colored, about 8 to 10 minutes.
Remove the onion, celery, and carrot from the bean mixture and discard. Remove the prosciutto, dice, and set aside. Drain the beans and reserve the liquid.
Add the fennel seeds to the onions, fennel and garlic. Add mixed greens and toss until they wilt evenly; adjusting the heat to keep vegetables from burning. Stir in the prosciutto. Add the beans, the reserved liquid, tomatoes, potatoes, zucchini, green beans, and jalapenos. Simmer gently until potatoes are tender, about 15 to 20 minutes. Add fennel fronds, if using, and season with salt and pepper.
Remove the jalapenos to a small bowl and discard the stems. Mash with a fork, adding a little broth and potato from the pot to make a thick puree.
Serve soup, passing the jalapeno condiment on the side.
Recipe courtesy Michael Chiarello