In a small bowl prepare garlic and measure out spice mixture, set aside. In another small bowl put finely chopped onions. Now chop your chicken into bite sized pieces.
In your non-stick 12 inch skillet heat oil over medium high heat.
Add 1/2 chicken and sprinkle with 1/4 teaspoon curry powder. Cook chicken until it is a nice caramel colour - approximately 5 minutes, stirring when needed. Chicken does not need to be cooked through at this point. Remove, set aside on a plate and repeat with remaining chicken.
In the same pan melt 2 tablespoons butter. Saute onions for approximately 5 minutes until transulcent and soft. Turn heat down to medium if onions are browning quickly.
To the onion mixture add garlic and spices. Continue stirring until garlic is cooked and spices are fragrant about 2 minutes.
Stir in tomato passata and reserved chicken and simmer for 10 minutes.
Add all remaining ingredients; cream paprika and sugar and simmer the sauce for 30 minutes until chicken is cooked through and sauce has thickened. Taste and add an additional 1/4 teaspoon cayenne pepper, 1/2 teaspoon salt and/or 1 teaspoon sugar if required.