Brown half the onions with oil;in a frying pan. Add the Schwartz for Chef Curry Madras Powder and cook for 2 minutes, stirring then add the chicken and brown. Place into a large casserole dish and remove from the heat and blend in the yoghurt, flour, stock, tomato purée and lemon juice.
Pour over the chicken, cover and cook in the oven for 1½ hours or until the chicken is tender. One hour before the end of the cooking time, add the remaining onions.