Soak the beans in cold water for at least 12 hours. Then drain them and cook in plenty of boiling water for about 1½ hours, until tender. Drain and season with two tablespoons of olive oil, salt, and pepper.
Peel the crayfish/medium shrimps, remove the intestinal vein, and sauté them in a pan with one tablespoon of olive oil for 1–2 minutes per side, until pink and lightly golden. Season with salt and pepper.
Next, toast the slices of bread on a grill or in the oven until crisp.
Finally, spread the warm beans over the toasted bread, place the crayfish/shrimps on top, and finish with a slice of lardo. The heat from the crostone and its ingredients will gently melt the lardo, enriching the flavor of the dish.
Serve hot, accompanied by salad or boiled leafy greens, dressed with extra virgin olive oil, table salt, and freshly ground black pepper.