Let’s face it. If you want to make anything sound that bit special, say it in French. A shrimp might be worth scoffing down. But a langoustine is something that has to be eaten with the reverence its embellished title deserves. Pommes Anna evokes crisp cotton tablecloths, silverware, crystal glasses and fine wines. With due deference to my eldest sister, “Anna’s potatoes” really doesn’t do much for the imagination. So when I cogitated preparing some sweetened duck legs in a plastic bag, it really had to be Duck a l’Orange Sous Vide. It may seem like déjà vu as I have done Duck a l’Orange here before.