Cut the cooking onions, ginger and garlic into smaller pieces. Put them into a food processor and mince finely. Skin and cut potatoes into quarters. Mix the curry powder with some water to make a paste. Heat oil in a non-stick Dutch oven. Stir-fry the minced onion mixture until fragrant. Add in the curry paste and stir-fry, mixing well for 2 minutes. Add the chicken and potatoes. Mix well. Cook, covered, for about 2 minutes. Add sour cream and water. Mix well. Bring to boil and reduce heat to simmer. Cook, covered, on low heat for about 30 minutes.
Curry tastes best if prepared ahead and served later with hot fluffy rice or a thick wholemeal bread.
