Grind together turmeric powder, garlic cloves, ginger, pepper, green chillies, small onions, curry leaves, fennel seeds, cumin seeds, cloves, cinnamon, cardamom and salt into a smooth paste.
Take 1/3 portion of the above and mix with vinegar/lemon juice.
Marinate the duck pieces with this mixture for 4 - 5 hours.
Heat half the oil in a pan.
Add the marinated duck pieces and fry for sometime (no need to fry it fully).
Heat the remaining oil in a pressure cooker and saute the remaining portion of the masala paste.
Add the fried duck pieces to this.
Pressure cook for about 30 mins approx.
For garnishing:- Cut potatoes into wedges and boil it.
Cut capsicum and tomatoes lengthwise and saute this in oil separately (should be crispy).
Garnish the duck roast with the above and coriander leaves.