Trim and score duck breasts, then cure with salt for 30 minutes. Wash and soak in bourbon for 30 minutes. Drain the bourbon into a container for later use and dry the duck.
In a pan lined with aluminium foil, add demerara sugar and the bourbon. Place the duck over the pan in a bamboo steamer, steam on medium heat for 6 - 8 minutes, then smoke for 10 minutes while the duck is resting.
White duck stock
Wash and peel the vegetables, then cut into mirepoix. Chop the duck carcasses and place in a large pan with enough water to cover them. Bring to the boil, add the mirepoix, bouquet garni and garlic clove. Simmer for approximately 2 hours, skimming occasionally. Add the peppercorns in the final 30 minutes, then strain through a fine chinois and chill.
Preheat the oven to 200°C. Peel the onion and cut into mirepoix. Chop the tomatoes and set aside.
Place the chopped duck wings and neck bone in a baking tray. Brown in the oven, then add the onion mirepoix and tomato paste. Cook in the oven for another 5 minutes then transfer to a large saucepan.
Add the chopped tomatoes, garlic, thyme, peppercorns and white duck stock to the saucepan and simmer for 4 hours, skimming regularly. Pass through a chinois, return to a pan and reduce slowly until slightly syrupy, then finish with honey vinegar and honey. Keep aside.
Bring the rhubarb juice to a simmer, skim then add the honey and chill. Add the Ultratex powder to the cold liquid and whisk continuously until the mix turns to a gel. Set aside.
Black tapioaca crackers
Boil the tapioca pearls in the water until fully cooked, drain then add the charcoal powder and mix well. Spread on baking paper and dehydrate at 50°C until semi dry. Preheat the deep fat fryer (or heavy bottomed saucepan) to 200°C. Fry the crackers until puffed and crispy.
Thinly slice the rhubarb stick lengthways using a peeler, cut the ends with an angle and place in an ice bath for 5 - 10 minutes.
To serve, cut the duck in half and place on a plate alongside the rhubarb gel, black tapioca crackers, duck jus, cress and rhubarb shavings.