1. Peel the onion and cut into quarters. Place in the bowl fitted with the ultrablade knife. Mix at speed 11 for 10 seconds. Replace the ultrablade knife with the mixer. Add oil, curry powder and ginger. Launch the P1 simmer program at 270°F for 5 minutes.
2. Add the chicken and tomato paste. Mix at speed 10 for 5 seconds. Launch the P3 simmer program at 200°F for 10 minutes.
3. At the end of cooking, add sour cream, cilantro, salt and pepper. Mix at speed 5 for 10 seconds. Divide each filo sheet into 4 strips. Place a heaping teaspoon of stuffing at one of the ends. Fold to make a triangle, then refold to the end of the strip and seal the pastry with egg white. Repeat with the other strips.
4. Cook for 2-3 minutes on high heat in a frying pan with a little oil; or bake for 15 minutes in the oven at 350°F on a cookie sheet lined with parchment paper.