In large frying pan, in hot oil, cook chicken pieces until browned on all sides. Remove chicken. In drippings remaining in pan, cook onions until browned. Stir in curry powder; cook 1 minute. Return chicken pieces to pan; add raisins, salt, brown sugar, and water; heat mixture to boiling. Reduce heat to low; cover and simmer 25 minutes. Skim off fat. Remove chicken pieces from pan. Stir flour with 1/4 cup water; stir into liquid in frying pan, and cook over medium heat until slightly thickened, stirring constantly. Stir in yogurt until smooth. Add chicken pieces and apple slices. Stir milk into biscuit mix just until blended. (You want soft dough.) Drop dough by tablespoonfuls into simmering liquid in frying pan. Reduce heat to low; cover and cook 15 minutes until chicken and apple slices are fork-tender and dumplings are set.