Boil vinegar in a saucepan until reduced to 110ml.
Melt the chocolate in a bowl set over a pan of simmering water.
Stir butter and reduced vinegar into the chocolate and refrigerate for two hours until firm.
Preheat oven to 150°C and butcher the ducks into legs and breasts.
Brown duck legs skin-side down in a pan, then add duck fat, one garlic clove, and half the thyme.
Roast duck legs in the oven for 60 to 90 minutes and keep warm.
Sauté shallots, garlic, and thyme in oil, then glaze with sugar, port, and chicken stock until thickened.
Sieve the sauce, season, and simmer with cherries for one minute.
Remove skin from breasts and roast flat between weighted trays for 5 minutes until crisp.
Pan-fry seasoned duck breasts in duck fat for 2-3 minutes per side and rest.
Place one leg on each plate and surround with carved breast pieces.
Top breast pieces with crisp skin, chocolate quenelles, cherry sauce, and cress.