Dredge the rabbit pieces in the flour. Heat the oil in a soup kettle. Add the pieces of rabbit and the onions and brown in the oil turning as needed for about 20 minutes on a low flame. Add the cider, turning the fir up momentarily. Using a wooden spoon scrape up the brown bits at the bottom of the pot. When the cider boils, add the potatoes and the carrots. Turn down the fire to a simmer, cover and cook one-half hour. Remove the cover and add the apples and cook another half-hour. At this point, boil rapidly until the liquid in the pot is about 2 cups. Make a slurry of two tablespoons of cold water and the cornstarch and add it and the parsley to the pot, cooking until the sauce is thick enough to coat a spoon. Plate the rabbit and vegetables and spoon the sauce over them.