Mix together ginger powder, cardamom powder, cumin powder, sugar and roasted rice flour in a small bowl and set aside.
Cut off the ends of the plantain.
Make a cut lengthwise down the plantain, just enough to go through the peel. Then gently remove the peel. If you're going to peel more than one plantain then it might be a good idea to oil your hands lightly to prevent the sap from the plantain skin from sticking to your hand.
Don't throw away the peel, you can make thoran with it.
Cut the plantain lengthwise and then cut them into half-inch pieces.
Unrefined coconut oil is absolutely essential if you are going for the authentic taste of Kerala chips. Heat 1 – 2 inches of oil in a pan to medium heat around 355°F (180°C). Drop one slice to see if the temperature is just right. If it bubbles and floats to the top you are ready to go.
Fry for a few minutes until it stops bubbling, at this point you can remove the chips from the oil and air fry them until they are crispy or you can continue frying them in the oil until they are done. If you choose to fry them in oil, make sure to reduce the heat to low to ensure they cook evenly.
Place them on a kitchen towel to drain and let them cool down completely.
Combine coconut sugar and water in a pan and bring it to boil. If you're using jaggery make sure to strain out the impurities.
Stir constantly until it reaches one-thread consistency or it pours like honey.
Quickly remove from heat and mix in the plantain chips until they are coated well.