Heat canola oil in a large saucepan over medium heat. Add apple, onion, and ginger to the saucepan. Sauté until the onions are beginning to soften, about 5 minutes. Add curry paste and garlic. Lower the heat to low, and cook for about 5 minutes, stirring constantly. Add beef stew meat and 1/2 cup water. Increase the heat to medium to medium-high and cook for about 10 minutes. Pour in the coconut milk. Bring the mixture to a boil, then turn the heat to low.

In a small bowl, combine ground coriander, cumin, and garam masala, along with about 2 tablespoons water. Stir to make a paste. Add the paste and potatoes to the beef mixture. Stir, cover the pot, with the lid ajar, and simmer for approximately 2 hours, or until the gravy thickens. Taste the curry and add spices to suit your taste. Serve over basmati rice, with raita (yogurt mixed with grated cucumber) and mango chutney.