In cold water, soak the fava beans overnight to soften. Drain and add the beans to a pot filled with fresh cold water to cover. Add the onion, fennel, and dissolved tomato paste. Bring to a boil. Reduce the heat to medium-low and let simmer until the beans soften and split, forming a puree, about 1 hour. Using your hands, break up the vermicelli into smaller-sized noodles. Add the vermicelli to the pot and continue to simmer until the noodles are cooked, about 15 minutes. Season to taste with the salt and pepper. In a small bowl, combine extra-virgin olive oil, tomato paste, and chiles and drizzle over puree. Allow to cool to room temperature before serving with the toasted breadcrumbs scattered on top. Garnish with fennel fronds and pepperoncino, to taste.
Recipe courtesy of Mario Batali