1. Add oil to a very hot pressure cooker pot.
2. Brown the cut up chicken pieces nicely on all sides, remove to rest.
3. Add the onions and sauté till light golden brown.
4. Add garlic and sauté until onions are dark golden brown.
5. Add the curry powder to the pot and stir until fragrant.
6. Add the diced apple, water, salt and pepper.
7. Return chicken to the pot.
8. Stir once again to distribute evenly.
9. Place lid on pressure cooker tightly.
10. Heat on high until the weight begins to jiggle. Lower heat immediately to a level that keeps the weight just barely moving. Cook for 12 minutes.
11. Remove pot from heat. When the pressure has been reduced, open the pot. Stir the ingredients very gently.
12. Combine 2 tbsp flour and yogurt together.
13. Stir some of the hot liquid from the pot into the yogurt mixture, then pour the mixture into the pot and stir to blend. Simmer for 5 minutes on a low heat.
14. Serve over hot fluffy rice.