Score the duck fat, rub with olive oil and season with salt and pepper. Leave to rest
Peel 1 sweet potato and dice, then boil in water until soft, 10 to 15 minutes.
While potato is boiling chop the savoy cabbage, garlic and shallot. Mix together and add to hot pan with olive oil, salt and pepper on a low heat until cooked through. Add a knob of butter towards the end.
Add duck breast skin side down to the hot pan with olive oil and cook until the skin is golden and crispy, roughly 4 to 6 minutes, then turn over to seal the meat. Leave to rest for 1 minute.
Drain the sweet potato and add to a food processor with a knob of butter and a little milk, salt and pepper and blend to a puree.
Mix hoisin sauce with honey.
Slice the duck when still pink in the middle. Then glaze with the hoisin honey sauce and serve with the sweet potato mash and cabbage.