Place the farro in a medium-sized saucepan and add water to cover by 2 inches. Bring to a boil and boil for 2 minutes. Remove the pan from the heat, cover, and let sit for 15 minutes. Drain the farro in a colander and transfer it to the work bowl of a food processor fitted with the metal blade. Pulse just until the grains are coarsely ground, 30 to 45 seconds.
Heat the oven to 275° F (135° C). In a large bowl, combine the farro, milk, sugar, salt, cinnamon, and lemon peel. Scrape the seeds from the vanilla bean into the mixture and add the pod as well. Mix well. Coat a 2-quart (2 L) oven-proof baking dish with a little oil—I use a soufflé dish. Pour the mixture into the dish and place in the oven. Bake the pudding, uncovered, for 3 ½ to 4 hours, until thickened and creamy. Stir it briefly every hour or so to prevent a skin from forming. If there is a skin, just stir it back into the pudding.
Remove the pudding from the oven. Discard the vanilla pod and the lemon peel if you can locate the peel; otherwise leave it in. Place a sheet of plastic wrap directly over the top of the pudding and refrigerate until thoroughly chilled.
To serve, spoon the pudding into individual custard cups and garnish with a drizzle of cream or dollop of whipped cream, if you like, and a sprinkle of cinnamon.
