Ceylonese Sweet and Sour Chicken Curry

Put the chicken backs, necks, and giblets into a saucepan, cover with water, and bring to the boil. Reduce the heat, cover, and simmer until the meat is falling off the bones. Strain and reserve the broth. If it is not very flavorful give it a little help with powdered bouillon. Melt the oil and butter together in a large, heavy skillet or casserole. Add the curry powder and stir about until slightly singed. Add the next 8 ingredients and sauté until the onions are soft but not yet browned. Add the chicken and brown well on all side. Pour in the pineapple juice and reserved broth and simmer covered until the chicken is tender. Add the sugar and vinegar and simmer for about 2 minutes. Taste. If you want a more distinct sweet and sour flavor add more sugar and vinegar at this time. Also add more cayenne if you want it hotter. Add salt to taste. Add the pineapple chunks and all the remaining ingredients except cornstarch mixture, stir gently, and simmer for 5 minutes. Add cornstarch mixture; stir and simmer until sauce is glossy and slightly thickened.