Whole spices such as Cassia, Mustard Seeds, Cummin, Curry leaves etc needs oil at a very high heat to start with (Tempering) they will spit and pop this is the best way for them to release their flavours then turn down heat for powdered spices.
Your oil will take on all the flavours of these hard spices ready for the next stage ie onions tomato puree etc.
Hope this helps
Layne
Your oil will take on all the flavours of these hard spices ready for the next stage ie onions tomato puree etc.
Hope this helps
Layne

