Mix the Nuoc Mam sauce, vinegar, onion,
juniper, berries, fennel seeds and garlic thoroughly in a large bowl and
rub well into the duck portions.
Cover the bowl with some kitchen film and
leave in the refrigerator for 8 hours, turning occasionally.
Preheat the oven to 220oC/425oF/Gas
Mark 7. Drain and reserve the marinade. Place the duck portions, skin
side down, in an ovenproof dish. Put in the oven for 30 minutes, basting
at least once.
Turn the duck portions over, baste and
cook for a further 30 minutes, basting at least once. Switch off the
oven but leave the duck in it.
Spoon 225ml of the marinade into a hot
pan, cover and allow to simmer for at least 5 minutes. Strain, whisk in
the yogurt and season with salt and black pepper to taste.
Serve the duck on a dish garnished with
the watercress. The sauce is served in a bowl. If guests are not
proficient with chopsticks, the duck should be chopped into bite-sized
pieces.
