Start preparing your sweet potato croquettes. They will have to chill in the fridge before deep frying so they are stiffer. Grate skin off sweet potatoes. Once cleaned, grate sweet potato into thin slices into a large mixing bowl.
Finely chop 1 onion and place in bowl with sweet potato. Add your feta, eggs and breadcrumbs.
Mix this all together well and place in fridge to chill.
Heat up your grape seed oil in a small saucepan. Once hot, add the other chopped onion and sliced garlic cloves. Cook until onion is a clear colour.
Add butter, 50ml of your cream and 3 chopped parsnips. Cook until parsnips are soft enough to puree (around 10-12 minutes). You will need to stir regularly during this process so you don't burn the puree.
While that is cooking, wash excess blood off your duck breasts and sprinkle course sea salt over the skin side of the breasts.
Start to heat up your oil until it starts to lightly smoke from the heat. Place the duck skin side down in the pan and cook for around 8 minutes until the skin is darkened and crispy.
By now your puree should almost be ready, so take it off the heat and put it through a sieve so that all the solids are separate. Place all solids into a blender or food processor and add remaining cream. Blend until a very smooth paste forms.
When you have your paste, put it in a bowl and slowly add the remaining butter mixture you used while cooking until you get a medium thick puree consistency. Place one side until serving.
Turn your duck breast over and cook on the meat side for another 3 minutes until a medium rare stage.
While the duck is cooking, heat up for frying oil in a deep fryer or deep pan. Quickly roll your croquette mixture into balls or small sausage shapes. Once all the mixture is rolled, place then in the oil (in basket or straight in if you don't have one) and cook until golden.
By now your duck should be ready. Take off the heat and place on a chopping board to rest for approximately 10 minutes.
Take your croquettes out the pool and place them on kitchen paper to drain excess oil. Quickly peel a parsnip into fine strips and fry those to make chips. When they are ready they will be a golden colour (3 minutes).
Heat up your puree slightly. Once warm, place a tablespoon in the middle of the plate and smear into large circle. Slice your duck into thin slices, and place around 4-5 cuts onto the middle of the puree. Top that with parsnip chips and watercress. On the side, add 2 croquettes. Serve immediately.