Heat the oil in a medium stainless steel saucepan.
Add the onion and cook over moderate heat, stirring occasionally, until softened, about 5 minutes.
Add the curry powder and cook for 2 minutes.
Stir in the tomato paste, then the wine, water and bay leaf and bring to a boil.
Add the thyme, oregano and 1/2 Tbsp of the lemon juice and cook until thickened and reduced by three-quarters, about 6 minutes.
Strain the sauce into a large bowl, pressing hard on the solids; let cool.
Add the mayonnaise, the jam and the remaining 1/2 Tbsp of lemon juice to the sauce. Fold in the chicken and currants, if using, and season with salt and pepper.
Refrigerate until chilled or for up to 1 day.
Sprinkle with the parsley and serve. NOTE: Since this is from a wine magazine, you didn't think they would leave out the best wine to serve with this meal, did you? Their recommendations: The sweet notes of apricots and currants point to a wine with some fruitiness and spice of its own.