Zuppa di lenticchie e porri

Prep and cook the lentils

1. Optionally, set the lentils in a large bowl covered with water by at least 8cm (3 in). Soak overnight (or at least two hours).
2. In a large pot, place the lentils, along with the garlic and bay leaf. Cover with water by at least 3cm (1 in). Simmer until barely tender. Add water as needed to keep the lentils covered. When they're done, turn off the heat, add salt to taste and let rest for at least 5 minutes.

Prep and cook the leeks

1. Meanwhile, prep the leeks by trimming off their dark green tops, then cut them down the middle lengthwise, and if thick again into quarters. If you see any grit, then rinse the leeks thoroughly, drain them and let them dry. Cut the leeks horizontally into large dice.
2. In a large saucepan, saucier or braiser, sauté the diced pancetta in olive oil over gentle heat until it's rendered its fat and just begun to brown. Then add the diced leeks and a small pinch of salt and simmer until they are quite soft and well reduced, usually around 15-20 minutes. Add a few drops of water from time to time to help the leeks along and prevent them from browning.

Putting the soup together

1. When the leeks are very tender, add the lentils, drained of their cooking water, to the pot. Stir the lentils into the leeks and let them simmer together for a few minutes, tossing from time to time.
2. Add enough cooking liquid from the lentils to the pot to cover the lentils and leeks entirely, along with the rosemary if using. Simmer everything together for another 5-10 minutes or so.
3. If you like a thicker soup (and I often do) crush some of the lentils with a wooden spoon or spatula against the side of the pot as they simmer, as many as you need to get the consistency you prefer. Conversely, if the soup is too thick for your taste, add more liquid, either the cooking liquid from the lentils, broth or water. At the end of cooking, taste and adjust for seasoning.
4. Serve hot, topped if you like with a drizzle of olive oil or a dusting of freshly grated parmigiano-reggiano, or both.