Hang the natural yoghurt in a muslin cloth over a bowl overnight (this will remove the whey and leave you with a nice thick yoghurt). Set aside until ready to serve.
Preheat the oven to 160C/325F/Gas 3.
Heat the red wine and soy sauce in a saucepan until it forms a syrup. Add the maple syrup and the chicken stock and continue to heat until it is reduced to a thick, sticky consistency suitable for glazing.
Heat an ovenproof frying pan until it is warm. Place the duck breast fat-side down in the pan and gently render the fat from the skin. Baste the breasts with the fat regularly for 3-4 minutes, ensuring the breasts stay skin-side down. Season to taste with sea salt and place the pan in the oven. Cook for 8-10 minutes skin-side down. Remove from the oven and leave to rest for 5-10 minutes.
In a saucepan, bring 500ml/18fl oz water to the boil with the sugar, pine and thyme. Cut four sticks of the rhubarb into small oblique shapes and place them in a bowl. Pour the sugar and herb infused water over the rhubarb leave for five minutes to soften, but so the rhubarb still has a bite to it.
Using a mandolin, shave the remaining rhubarb into wafer thin slices. Season with sea salt and leave to cure for 5 minutes, then set aside.
For the rice, heat the oil to 210C/410F in a deep pan or deep-fat fryer. (Caution: Hot oil can be dangerous. Do not leave unattended.) Carefully add the rice to the oil. It will burst and float to the top. When they have stopped popping, remove them from the oil and drain on a plate lined with kitchen paper. Season with sea salt.
Shallow fry the pumpkin seeds in a frying pan with 50ml/2fl oz of oil until they puff up. Remove from the pan, season with sea salt and drain on kitchen paper.
Slice the fennel lengthways on a mandolin and season with lemon juice and sea salt.
To serve, spread the yoghurt across the plates. Glaze the duck breasts with the soy glaze, then coat with the rice, pumpkin seeds and mustard seeds. Carve once lengthways down the middle. Scatter the poached rhubarb and salted rhubarb over the plates. Place two slices of fennel on each plate, add fresh watercress and drizzle with pine oil.