Peel and wash fresh fava beans (small if possible) under running water. In a pot (preferably clay) over low heat, sauté chopped onion and diced guanciale until golden.
Add fresh fava beans and season with salt and pepper. Cook over medium heat for about 15 minutes, adding warm water if necessary. Serve warm.
If you are using dry fava beans (preferably ""angiane""), boil them first, then follow the recipe. When sautéing, remember that they will need less time compared to fresh, uncooked ones. Deglaze with a small amount of dry white wine.