Heat 2tbsp oil in a medium sauce pan; add red chili flakes and cook for 15-20 seconds, make sure not to burn them. Next add onions and saute them until soft, about 4-5 minutes.
Add peppers and ginger, cook for 2-3 minutes. Next add chopped mangoes and cook for 1 minute.
In a measuring cup, combine pineapple juice, vinegar, sugar and curry powder. Whisk well to combine.
Stir this into the saucepan, mix well and bring the mixture to a bare simmer. Reduce the flame and cook for 30 minutes, stirring frequently.
Add the raisins and cook for 2 more minutes.
Turn off the heat and let the chutney cool completely before transferring into clean jars for storing. Keep in the fridge for longer shelf life.