Soak the beans overnight. The next day, rinse the beans well, then put them in a pot with at least 3 liters/12 cups of water. Add the garlic, sage, salt, and peppercorns, as well as the pancetta or prosciutto if using. Bring the beans to a boil, then lower the heat and simmer them until tender, about 45-60 minutes, depending on the beans.

Meanwhile, make your soffritto: heat the olive oil in a casserole, preferably terracotta or enameled cast iron. If using the lardo, mince it finely and sauté it gently in the olive oil until it has rendered most of its fat and slightly browned. Add the onion, carrot and celery, and let those sauté gently, too, until they are tender and the onion has turned translucent.

Add the kale, mixing it well with the soffritto so the kale is covered with the seasoned oil and aromatic vegetables, then let it cook down until the kale is wilted and well reduced.

When the beans are cooked, add them along with their cooking liquid to the casserole, topping up with water (or broth) if the vegetables are not covered. Simmer over a low flame until the kale is perfectly tender, about 30-45 minutes. Stir from time to time, and add water if needed to keep things loose. Along the way, you can crush some of the beans against the side of the casserole with a wooden spoon to thicken the soup.

When the kale is tender, add the polenta to the casserole in a thin stream, stirring all the time so it mixes will into the soup without lumping together. Continue simmering until the polenta is fully cooked, usually another 20 or 30 minutes. Add more liquid if the farinata starts to dry out. It should have the consistency of porridge.

Serve while still hot, with a good filo d'olio (drizzle of olive oil) and freshly ground black pepper.