Put beans in pot and cover with cold water. Soak for 8 to 10 hours or overnight. Drain and put beans back into pot with carrot, celery, garlic, whole onion and 8 cups of water. Bring to a boil. Skim surface if necessary. Reduce heat and simmer for approximately 45 minutes. Check beans for doneness. They should be soft and creamy, not too mushy. Season beans with salt towards the end of the cooking time.
While the beans are cooking, saute the onion in olive oil in a large skillet until onion is softened. Add the pancetta and continue sauteing until onion and pancetta are golden but not too crispy. Add the red pepper flakes and season with salt and pepper. Stir in the rosemary and saute for one minute. Remove pan from heat and cover.
Take the beans off the heat once they are cooked. Remove carrot. Throw out celery and onion. Lift out an abundant slotted spoonful of the whole beans and put into the pancetta pan. Take 2 tablespoons of the pancetta mixture and add to bean pot. Cut up the carrot and add to pancetta mixture. Using an immersion blender, puree the bean mixture until completely smooth. Add the pancetta mixture, stir briefly and bring to a boil. Stir in pasta pieces and cook until pasta is tender. If soup is too thick, add a little hot water.
Serve with grated cheese and a swig of olive oil.
The ingredient list omits the eight to ten hours of hydration dried roman beans require before hitting the heat. Soaking dissolves complex sugars and hydrates the starch granules evenly, preventing split skins during the initial forty-five-minute boil with garlic, carrot, and onion. Salting the cooking water too early hardens pectin in the seed coats, so add salt only during the final minutes of simmering once the interior albumen yields to pressure.
Building the Aromatic Base
Sautéing chopped onion and pancetta in extra virgin olive oil requires medium heat to render internal fat without burning the milk solids. Fresh rosemary added during the final minute releases fat-soluble volatile oils into the pan rather than bittering from prolonged contact with direct heat.
Blending and Texture Management
Dividing the solids creates textural contrast. Pureeing the bulk of the tender beans with an immersion blender builds body, while whole beans and chopped cooked carrot folded back into the purée provide distinct bites. Fidelini pasta cooks rapidly in the boiling starch suspension, absorbing liquid quickly and requiring adjustments with hot water to maintain a fluid consistency.