In a large skillet, combine the fava beans, guanciale, artichokes, and onion, drizzle with the olive oil and cook over a medium-high flame, stirring regularly, until the ingredients are softened and browned, about 10 minutes.
Season with salt and pepper and add 1/2 cup water. Continue cooking for another 5 minutes, then add the sliced potatoes, adjust the seasoning, cook for an additional 2 minutes, and remove from the heat.
Preheat the grill or broiler. Grill each slice of bread until it is golden brown on both sides and top each with some of the vegetable mixture. Serve while hot.