The dish is composed of white sweet potatoes cooked in and glazed in a red wine pork rib jus. The potatoes are simmered in this intense broth and are able to retain their shape and structure based on the technique of soaking fruits and vegetables in high calcium solutions. The technique stems from the brilliant work of Andoni Luis Aduriz of Mugaritz and Paul Liebrandt of Corton we observed at Star Chefs. Andoni uses slaked lime as his calcium source, referencing the technique of nixtimalization. If you look closely at his approach he is using raw fruits and vegetables and soaks them in the solution rather than cooking them in the lime solution. This evolution shows an understanding of the history of cooking as well as the knowledge of the reaction between calcium and pectin. Paul's take on the technique uses calcium lactate to soak his vegetables rather than slaked lime to achieve similar results. Paul's use of calcium lactate was the aha moment for us pointing out the pectin-calcium reaction which we have exploited in the past and had not looked at in this case. The soaking in the the calcium allows the pectin in the potato to react with the calcium in the bath to form a thermo-irreversable gel and allow the vegetable to be cooked in a skin of itself. He showed that we just needed a calcium source to form a skin around pectin rich fruits and vegetables rather than specifically lime.
In our dish we soak white sweet potatoes in a bath of water and 3% calcium chloride. We chose to use calcium chloride for its high amounts of available calcium in order to achieve a skin around the potatoes. Calcium chloride has about 38% available calcium while calcium lactate has about 12% available calcium. We chose not to use slaked lime since Paul demonstrated that other calcium sources were available for us to choose from. (In future dishes we will look at using calcium lactate and gluconate especially with porous vegetables and fruits to avoid the bitterness of lime or calcium chloride which can be absorbed and be carried into the dish. We did not have any problem with the sweet potatoes but slaked lime reaped havoc on Asian pears.) After soaking the potatoes for 3 hours we rinsed off the calcium solution and simmered them in the rich pork jus. The potatoes softened on the inside while the outside retained its structure and shape. When we cut into the potatoes we could feel the delicate textural difference in them. The rich meat jus penetrated the "skin" of the sweet potato and partially into the flesh leaving the actual interior white. We paired the creamy meat potatoes with carrot crisps and puree, horseradish cream and charred lemon balm leaves. It is a delicious expression of a Sunday supper.